Someone replaced the cat and said they got some good gains.

 

that b a strightpipe..n yes its does gain

 

No they replaced the stock cat w/a high flow one.

 

after replacing the stock cat w/ a random tech cat someone actually lost alot of low end torque and hp. and gained minimul hp's in the high end.

 

i think it was Ogolden1 with the random tech hi-flow cat wasn't it?

 

haha even though me and you have it... i'm sure most members on the board wouldn't do it...

 

As stated before, 1" less back pressure = 1 HP gain, just a general concept but seems to fit in this case. Out catalytic converters have about 1" - 1.5" pressure drop per every 100 CFM. Our cars will flow about 400 CFM max. That is a maximum of 6" back pressure.

If you put in a high flow catalytic converter, say with 50% more flow capability, you can expect to gain a whooping 3 HP...

Just keep to a good brand of gas and retain that same amount of HP.

 

the main reason i opted for a hi-flow cat was due to the 100 shot. i also have 2-1/2" piping & a 2-1/2" custom y-pipe. the low-end loss is minimal but above 4k rpm in combination w/ headers & my ignition, the output is definitely worth it even if you're not spraying like i am. i hope this helps.

 

any thoughts on completely removing the cat? how much HP do you think is gained by taking it out completely and replacing it with a straightpipe? scalbert?

 

As shown above, there is limited HP to be gained. But with that aside, the emissions testing (don't they have visual in CA??) and subsequent fines if caught (along with the limited power gain) make it not worth while IMO...

 

hmm... yah i know if caught i could be in big trouble... but as PimpinWhiteCL-S can confirm as well, when we drive on the freeway and floor it, the pull seems be much better and the car picks up faster; a noticeable difference in power

 

a buddy of mine did remove it completely for his nitrous w/ a straight pipe all the way back from the headers & had it bolted on to the stock y-pipe.

this definitely makes you lose a lot of back pressure.
my system was constructed w/ keeping the right amount of back pressure in mind. this is why i also welded a resonator to suppress some of that free-flowing sound & to minimize back pressure losses.

-an axle-back exhaust (2 mufflers) will not give you any gains
for $500.
-the greddy cat-back will give you more gains for $800.
-my system is very free-flowing but was all custom mandrel bent for a total of $900 including the HKS mufflers, hi-flow cat, resonator, mandrel-bent 2-1/2" piping & y-pipe, & all labor charges.

there are minimal amounts of torque losses, but definitely huge gains in the higher rpm's. the sound is incredible as well. it all depends on what you're looking for. i would definitely recommend it to anyone looking for gains.

hope that helps.

 

Dynos dont lie. Sure I gained HP, but lost a lot of low end torque. Johntypes also dynoed his car with the same results. Just stick with the stock one, unless you have a supercharger.

 

hmm... too bad you're not in california... or else i could refer you to the muffler shop me and pimpinwhitecl-s went to in Palmdale, CA. they completely redid his piping (2.5'' as well from headers, redone y-pipe, straightpipe) for $120.

 

damn, that's a deal for $120.
the thing is there's only one mandrel-bending machine in all of Florida. that's probably the $$$ difference!

 

hmm... probably. i'm not sure if his piping is mandrel or crush bend though.

 

Probably crush bend...mandrel is a specialty shop thing...it requires a special machine that is not cost feasible unless you do a lot of custom exhaust work...the difference is maybe 2-3 hp gain depending on the bends...so, as great as mandrel bent piping is supposed to be...it doesnt offer incredible gains over crush bending. Especially when you consider from the cat back...there is one slight bend...and then the Y-pipe. Keep your cat unless your using fi (nos,sc, turbo). I'm using 2 1/4" right now...and it is big enough over stock that you get a good combination of torque and high end power.

 

i thought stock IS 2.25''???

 

Stock is 2" at best.

 

hmm... never knew... thanks for the info

 

2" ID for sure, the OD measured in at 2.15"

 

Not a prob...i thought they said we were getting a higher flow exhaust system...they lied...I guess the mufflers are less restrictive if anything. I took it to the muffler shop and wanted 2 1/2" and the guy looked at me weird...he was like 2 1/4" is probably the max...I was like WTF!?! That is civic sized piping...but he told me that it was 2" piping at the largest, probably 1 3/4".

 

Hey D-GTS, I've read in your post that you have Aem underdrive
pullies. I thought that AEM only makes power pulley...

 

I read in sportcompact that all new vehicles cats are pretty much pushing the most HP out of them already and its almost pointless to get a hi-flow cat.

 

Does anyone know how restrictive the resonators are? Is it worth getting a resonating tip with stock resonators in place?

 

Does no one listen to you? AHH well, they will learn.

 

Get all the sound deadening you can...if you increase the pipe diameter....and remove the resonators you will pay!!!
Ah well...I'll get a new resonator welded back on next week.

 

i really doubt sportcompact saying that. no catalytic can flow max power while still being carb/emissions legal. i live in florida & we don't have emmissions anymore. if i wanted, i could simply have a straight pipe, but we all need back pressure.

 

Dude, why would I lie? I am just stating something that I read, I have no reason to make up shit.

 

DUDE!
reread my reply & point out to me where i called u a liar. i said i doubt the validity of sport compact magazine's comment.
RELAX, DUDE!! GO CATCH A WAVE OR SOMETHING.

 

Looks like the jury is still out on this one. Some who did it say it works and some who didnt say it doesnt work. I am going to do it to my 3.0 and I will let you know how it turns out.

 

First of all...
I thought the only thing that needed backpressure was desiel engines....

Secondly:
I would think that the headers were designed to provide enough backpressure, because after the headers the rest is just free flowing..

Take a look at the pic... an eletric exhaust cut out... You weld a Y branch off the piping and install this bad boy before the Cat...

I am seriously thinking about since I am getting the SuperCharger... that son of bitch will scream down the track or scare the shit out of some little old grandma at a red light.... you can open it up a little or open it up alot.. open and close within 3 seconds... badass... 188 bucks too...shipped to the door with the switch....

Smitty

 

Dynoes dont lie. I actually dynoed the car to see the difference. After I installed the cat I noticed that the car felt weaker. I actually paid the money to find out. To my surprise the cat KILLED my torque. The same thing also happened to johntypes.

 

no, all n/a engines need backpressure to perform properly.

most diesel engines are turbo, so the less backpressure the better.

same goes for turbo gas motors.

allmotor would see serious performance gains from running a free flowing (large diameter) exhaust on his car.

thats why he dyno'd so much higher w/ mufflers unbolted.

 

I am (confused), here... Are you trying to say that with the CAT REMOVED you lost Torque. You stated in one post that you lost torque with it removed and now your saying with it installed it killed your torque....

I think it would seriously be alot of fun and hell of alot easier than unbolting mufflers..

I got a long awaited appt. with my exhaust specialist that does all T304 mandrel bent stainless exhaust work... I want tru duals with the electric cut out... I think it would be awesome for when I get the S/C..

I was thinking 2.5 (eletric cut out 2.5), upgraded stainless Hipo stainless cat.. into 3 inch duals..
We will see what he says..

But the cut out is just an option for you guys when you run track or want to have some fun with the neighbors... you can flip the switch and close it and run back into you stock set up...

 

before changing cat hp was 224 torque was195.1 put random cat on hp want to 242 but torqe droped to 185 lost to much low end car felt terrible put stock cat back on felt good left it that way.