Just asking again cause i know some one has to have this combination......Does anyone have a 5AT, with CT headers a RT CAT & exhaust? Please let me know if you fit this catagory and if you have a rattle or not?

Mini update, i didn't have time to get under it but the sweet spot is exactly from 660-695RPM's in which the different rattles occur!! I watched it like a hawk when driving around this weekend.



Reach, did you notice a difference in performance from your Topspeed compared to comptech? Also, did you notice ANY difference once adding the CAT at all?

 

I get a rattle when the ac is on with ct headers magnaflow high flow cat and fujitsubo exhaust.

My cat makes a rattle with the header even more when it is a rainy day but thats normal for me. before cat i had rattles with ct headers i just figure it was a natrual resounance that the flex pipe is shorter and is getting pulled by the exhaust system by the hangers therefore not really dampening much at all.

I did replace the cat rubber hanger and it did solve the rattle when the ac is on but according to my look that rubber hanger is still getting stretched so occasionally when the ac is on and im at a light i get the rattle.

 

Hey Jeff, is your rattle occur in the same RPM range as mine, 660-695PRM's?? Did your CAT and exhaust change the RPM's of the rattle at all?

 

hmmm, the header allows a lot more exhaust flow out of the engine, then it all bogs down at the cat and exhaust which flows less than the header, maybe that could cause the rattle with added turbulence. JWood, this is no fix but would be an interesting experiment, disconnect the cat and exhaust and run just the header, it'll be louder than crap I know, but would be interesting to see of the rattle dissappears, then you could rule out some of the header mounting issues and focus more on the cat and exhaust as the issue, or just remove the driver side muffler which is removable after the Y and see if that helps out by letting the exhaust flow a little more freely???

 

Might be true, when I have DC Header + High flow cat, I will get an ocassional rattle (once in a week) @ cold start especially in low rpm @ a start. However, once I have the Greddy SP2 install, I've never experienced the rattle again.

Will report back if I get a rattle in the future.

 

Im telling you its because comptech's header is about 1 inch shorter than our stock header so the comptech header is pulling the exhaust system towards the engine.
Problem about it is the flex pipe is pretty stiff, and the only thing holding the header is the engine, then exhaust and that one rubber hanger which is being pulled if you check it out its over streched.

When i installed my headers it made my exhaust tips look really short under my car. so when I got the highflow cat i was able to get the right length for the exhaust tips to stick out.

 

do you guys really think that spending 500 on this headers worth it though?

 

Yes and no, if you keep a watch on the black market you can pick up a used good condition comptech header at a reasonable price like I did. But the DC sport header does the job but has had a flex pipe issue which I think the newer generation fixed? However; I like stainless steel construction more than steel/ceramic coated construction but I suppose that is more of a personal opinion. However; a header deffinately registers on the butt dyno and IMHO that is worth the money.

 

Clee - That is a good idea and i might give that a try. I have a little time i plan on investigating thing weekend and if i can i'll try something along those lines.

Jeff - I have a feeling you may be right and if that is the case, do you think a spacer might solve it if there even is such a thing? So the comptech headers are a little shorter, are the high flow CAT's shorter than stock too? If that is the case then you would need to go with full header, CAT, exhaust setup in order to get it flow properly. And after you did this, your rattle decreased a little correct?

I am still thinking that a custom bracket will work whether it be on the header itself, or maybe even on the CAT, like another rubber hanger.

 

do you have an AT? It all depends on if something like this would bother you or not. If i can't fix it i don't see myself keeping it for a long time because it does bother me more than i thought it would. However, i knew it was a possibility going in but i like the challange and i'm an engineer so i knew i would try to fix it if i go it.

 

Regardless of what is causing the rattle (ie: new header), find the source of the sound itself. If you can clearly see that there is an area of the exhaust that is awfully close to something not attached to the exhaust, then test your 690rpm theory while looking at that area. If its rattling there, then determine why (ie: is the whole exhaust 1" closer to that area than it was before?). If it is, then I think you can look into getting a 1" extension on the exhaust at most exhaust shops, or, have a shop alter the bend of the pipe in that area or lastly, use your ingenuity to create some kind of bracket that forces the exhaust back a bit. I think that might have too much stress at that point though and cause further problems. I'd go with the 'customize the oem exhaust' route, or, get a new cat that you can order in a length 1" greater than the OEM cat...

 

Good to see so many gearheads working on this.

 

^^ Do you have any rattle with the Topspeed header Jan?

 

Nope.

 

So i got under the car friday night to try and get a better idea of what was happening with this and here is what i found. I jacked the car up, propped the brake so i could put the car in drive and leave it jacked up, and crawled under. When it was in drive at its normal 600-650 RPM idle range, there was a very slight normal vibration with no noise. I turned on the lights first and it raised the RPM's to the 680ish and caused a little more vibration but thing really bad BUT there was a this odd noise coming from the first resonator before getting back to the rear mufflers. There was also this noise in the driver side muffler that sounded like there was a piece of metal caught inside of it somewhere just kind of rattling around, it was was odd. I then turned the AC on, and this is when things got interesting. Since it was already pretty cold old, i turned the heater on in my garage, and set the AC to LOW, like 58 degrees or whatever it goes down to. When the AC really kicked on with the fan, the connection of the header and CAT, and mostly the CAT started shaking like crazy. I mean this thing was moving pretty darn quick and producing this odd vibrating noise from in and around the rear of the CAT and the first resonator in the exhaust. I put gloves on and i pushed the whole system up right around where the rubber header hanger was and it helped a little with the noise but NOT the vibration, this thing vibrated my whole arm and shoulder. I then moved backwards to the first resonator and pushed that up and that helped with the noise, but again, not with the vibration. The vibration was using the exhaust as a tuning fork to dampen out the vibration which is exactly what i thought was happening. Then the AC kicked off and the fan turned off and it went right back to the minimal vibration with that little noise and then when it kicked back on again, the vibration came right back. I turned the AC off, turned the lights off, and it vibrated as it hit that RPM range and then when to it 625ish idle speed and was soooo smooth.

Conclusions so far....
1. It is NOT the header itself, as it doesn't shake at all in the area where its connected to the engine. It only shakes in the flex pipe area and i think this is because of the exact reason that Jeff had mentioned due to it being 1" or so shorter than the OEM header.

2. A custome bracket at the base of the header would not be effective at all. This resonance is too WAY too strong to try and stop it, i really think that if i tried to redesign the rubber hanger area (this is where the majority of the vibration occurs) it would cause more problems somewhere else in either the CAT or the exhaust, however, it may be an option.

3. I am going to try those shorter exhaust hangers that JTso had used to pull the exhaust up and i think this may help eliminate the noise that comes from the first resonator at least, but def NOT the vibration.

4. Once i try these hangers i will take another look to see i can do something about flex pipe area header hanger. This is where i have a question. Those brackets that JTso mentioned, they won't work for this hanger will? There is soo much vibration that occurs there it looks like it will stretch that rubber hanger out in no time however, i don't know what it looked in stock form before this, which is something i would like to analysis as well. Does anyone on here live near Langhorne, PA? If you do PM me if you have a fully stock TSX or if some one can just watch there header and CAT with the lights and AC on just to see if there is at least a presence of a vibration.

I'm going to try and take a video of this so you guys can get a better look at whats happening, it may help some of the other "gearheads" as Jan calls us

Thoughts, comments, suggestions?!?!

 

Oh yea and i forgot one other thing. The rubber hanger that holds the flex pipe area, is there another stiffer rubber hanger that could be used just like the ones that JTso mentioned for the rear of the exhaust? Its different then those and if i can find a stiffer slightly shorter one as well, that might help a little too. OR, maybe even just add another one to the already existing one if it will fit to help beef up the area to help eliminate SO much movement. Again however, this may not be the best idea due to the amoung of movement.

I still can't help think that a high flow CAT would allow all this air to flow through a little faster creating less resonance. Reach, and others, when you put your RT CAT on, did you notice at least a slight decrease in the rattle, vibration, or noise?

 

Jwood, could you take the OEM rubber hanger to a NAPA or something and just compare it to a bunch of hangers there and see if you find a match. I got my rear exhaust hangers at NAPA and they had a ton of others there that I saw. Worth a shot.

 

Damn, good work Jordan!

I believe there are polyurethane hangers available at Autozone and other parts stores. They will be stiffer than regular rubber, but I'm not sure how resistant they will be to stretching over time with the vibration you are talking about here. Definitely worth a shot though as they aren't expensive.

You still didn't answer the questions of where the noise is being generated from. IE: What is banging against what, to cause the noise? We know the noise is being brought on by extreme vibration, but without something hitting something else, you wouldn't have a noise, would ya.

Is the noise you heard while under the car, the same as the noise you hear when in the car (and the noise that brought on this work)?

 

I'd recommend getting a few sizes... progressively shorter, if possible. Maybe there will be one size that creates a sweet spot where the noise and vibration are minimized.

Overall I think the vibration is somewhat normal... I mean how often do you see exhaust tips vibrating? Quite often. But EXTREME vibration and noise shouldn't be normal.

 

HAHA....good and simple idea Serf!! I may just have to do that on saturday.....not sure why i didn't think of that

 

That is the thing, there is NOTHING hitting anything and thats why i think it is strictly air vibration resonace that is causing this noise. I can't believe it but i am still looking for something but i think the noise is the reverberation of the shaking of the CAT either off the heatshield or the first exhaust resonator that is causing the noise. As for the noise in the rear exhaust can, that i need to look more into as i ran out of time and couldn't figure out much with that yet. But when i pushed the whole system up hard, the vibration noise decrease a little. This is why i want to try the shorter hangers.

As for the ones that JTso mentioned, would they bring up my stock exhaust too high and possibly hit my bumper, or is that much difference? I just ordered them in hopes i can do it this weekend!

And yes, the noise under the car is the same noise i hear in the car just sounds like it comes from different locations, but its somewhere primarily in between the header CAT connection and the end of the first resonator can......i will try a new rubber hangers for both and see what happens. Start with the cheaper solutions first

As for the exhaust, it doesn't really vibrate all that much from the back, and more than normal. If you touch you can def feel it, but can't really see it that much. I think by the time it gets to the rear muffler, the CAT and resonator have dampened it out enough. I actually think that raising it up might make the exhaust shake a little more due to lack of being able to dampen it out, but we'll see. If the tips shake a little more and the noise gets decreased, i will make that sacrifice.

Only thing i have thought about if this doesn't work, is go to an exhaust shop and talk to them about a small extension piece either pre or post CAT to extend it to make up for the shorter comptech header size.....but that is more $$ and more complicated so we'll see if i get to that point.

 

To me this sounds (pardon the pun) like a header problem. The header is probably optimized for best efficiency at high RPM (high flow) but somehow suffers from a resonance at low idle. You can try to dampen and physically isolate the header/exhaust with the purpose of minimizing the rattling but you will not prevent the vibration from happening at that RPM. I suspect its just unanticipated result of the header design (4-2-1 and dimensions). It may be easier to just avoid the RPM all together by raising the idle speed (by, say, 500 RPM).

 

That would be exactly what i would want to do but i have NO idea how to "move" the RPM idle speed. When the lights are off and the AC its SOO smooth at like 600-650 RPM's and then the lights or AC go on and up it goes. So maybe if when you turn it on, it could go up what it is when its in Neutral, that would be perfect! I don't know how that could be done or who could do it that is why i was trying to get a feel from the guys that had a RT CAT, hondata, and exhuast to get a feel for if the whole system changes anything like that.

I am on the path with agreeing with you Jan. I know its a header problem but more importantly that connection area. Like i said above, there is not going to be any way to stop that vibration so i just plan on trying to minimize the vibration so that the annoying noise at least goes away which i think is just the nature of the beast per say (meaning the air resonance ar that RPM).

I had my buddy take a look at it too while i was under there and when i turned the AC on and he say it start to shake, he was like "Holy crap dude, that thing can't be stopped and if you do it will cause problems elsewhere!" which was my exact thoughts. At that RPM its pretty bad and i honestly don't think you can "fix" it. So, i plan on just trying to smooth out the dampening process for it and we'll see where that goes.



EDIT: Sorry my posts are long guys, i am kind of talking out loud on some of these to just get my thoughts down for both myself and others to try and chime in and maybe together we can come up with a few ideas, which i think we laready have to at least get a starting spot.

 

OEM header for the win!

seriously though, the comptech one is just not beefy enough to handle the vibrations caused at low rpm wth AC on.

i commend you for your persistance with overcoming this issue. i gave up and went back to OEM. it is definately a shame that this happens though considering cost of comptech's header.

 

haha....yea! Thanks though jigga. I do not plan on spending that much money in trying to remedy this "issue" so we'll see what happens when i replace the rubber hangers and see what the exhaust place says. I'll be fine for the winter but come spring when the new TSX comes out and or its time for the AC to be on more often, i might need to swap back or give the Topspeed header a shot if it still bothers me.

 

Some thoughts...

Maybe a beefier battery and/or a better ground will help when the lights come on.

I doubt it but maybe lighter pulleys might make a difference. The advantage of the lighter pulleys is that there is less rotational mass which makes changes in the rotational mass easier to accomplish (i.e. engine RPMs spool up faster). I'm not sure if the lower rotational mass would make any difference at a constant RPM (at idle) while the A/C compressor clutch is engaged.

Just food for thought.

 

His thoughts are mine exactly. If you try to stop the vibration mid-pipe, you might cause some serious stresses on connections and flanges elsewhere (cat/header, or cat/pipe, or even header/block). This would obviously be very bad, as you know from being a bridge engineer!

When you pushed the exhaust up and minimized the vibration/noise, did you push on the pipe itself, or did you lift the exhaust via one of its existing hangers? If the former, then you might be in for a bad surprise when you move the exhaust up with new hangers, as it might have been your hand/arm absorbing the vibration and thus the noise, and the minimized vibratino/noise might not have been a result of physically moving the exhaust up vertically. As I said before, though, it wouldn't hurt to get the stiffer, shorter hangers and give it a shot, but after that I don't know what the solution might possibly be.

I doubt air itself will cause the actual noise, however. Something is banging on something else, or resonating... one or both of the two. Try removing the cat heat shields (top and bottom) and see if the noise disappears then. They are flimsy and can likely vibrate like mad, causing all kinds of noises. I removed my upper and lower cat heat shields after the shields rusted enough that they came loose and made an awful racket at certain rpm. That rpm was when just starting in a 6MT, so likely just below the 750rpm idle. Let's say 650rpm. Sound familiar? I thought it was a transmission problem until I started banging on stuff with my hand, and reproduced the noise when I hit closer and closer to the cat heat shields. Ripped them off and the noise was gone.

 

The Comptech header is not that much shorter than stock and neither is DC when people attributed the flex pipe separating years ago. You will see a gap between the header flange and the cat when they are separated during the header installation regardless it's oem or not. The gap seems to indicate the exhaust system being a little short by 1/4" to 1/2". Keep in mind that just because you see a 1" gap doesn't mean it needs 1" to fill. If you add 1" to the exhaust setup, you may risk running the exhaust rear section against the RSB or the rear bumper. Pulling the gap together will stress the exhaust hangers and cause them to lose the flexibility to absorb vibrations.

Since you have an aftermarket cat, the simplest way to reduce the gap without welding on a new section is to find the correct size exhaust flange, preferablely with the ideal thickness and the matching gasket. Then use longer nuts and bolts to attach them together.

 

Actually, doesn't the exhaust 'stretch' once its warmed up anyhow? Expanding properties of the metal and such.... I recall reading this somewhere recently and it made sense at the time.

 

Yes, it does stretch another 1/4" or so when it's hot. You can measure the tail pipe and use the exhaust opening as reference.

 

Jan, that is possible and a good idea. Going with that, does anyone that has pullies notice a change in idle at all? JTso monitored and measured the voltage change so maybe he knows more about this? In theory it makes sense but it might not be significant enough to change it enough.

 

Good points Eric, which i agree with and have been thinking about. As for when i pushed up, it very well could have been my arm absorbing some of the vibration. Two things i want to try this weekend are to a, remove the heatshield from around the CAT and b, use the jack or metal to push up the CAT instead of my arm or at least something more rigid. I pushed up on both the hangers and the CAT itself, which started to burn me through my gloves....lol

 

I don't have an aftermark CAT actually but i keep thinking that it would help increase the air flow through that area that would help eliminate the congestion in that area.....in theory it should be better but i want to hear from others that have the RT CAT and still have the rattle. I am waiting for Reach to read this again.....

With that little of a difference its hard to compensate for it. Do you mean that if i were to buy an aftermarket CAT, that i could just get a thicker flange and gasket to make up for the shorter length? I guess the RT CAT's flange isn't any longer than stock?

 

The change in back-pressure that the header flange sees due to an aftermarket cat (and/or exhaust) may make enough of a difference to shift the resonant frequency low enough. Its just hard to say ( it may shift the frequency higher ). I think you're doing the right think by polling people that have the header and different cat/exhaust combinations.

 

Yea, it just sucks that not that many people seem to be responding. Can i add a pole to the beginning of this tread, or could you do that Jan? PM me if you can i'll set something up. Jeff said his decreased a little bit but he has pulies, CT headers, RT CAT, AND exhaust so that is a big change there.


Otherwise, everybody, PLEASE post up some info for me if you have a AT with comptech headers and if you have the rattle, at what RPM range and more importantly IF you have a CAT or exhaust! This will really help me out, thanks!

 

AT with Topspeed Header, stock cat and stock exhaust. No rattles here.

 

why is poll only for AT owners? i had 6mt with comptech header and got rattles...

 

Its less known with our MTs

 

Oh really? I was under the impression from reading the other forums on this that no one with a 6MT had rattles because when your typically at a light, your not "in" gear. You may be in it, but your clutch is in and therefore idle at a higher RPM.

Yours rattled when and what else did you have installed? RPM range as well?

 

^^Us 6MT guys got it with the A/C on sitting at idle in traffic.

I have the CT Header and Cat back and RT cat. When I got under the car and looked around, I had nothing touching. It sorta went away.