I have straight pipe and my engine check light wont go off. Anyone out there able to correct this problem? Also, will the Comptech headers work better cuz i have no catalytic converter?

 

Of course it'll work better but i wouldnt' keep your car that way cause there is less restriction.

 

The exhaust system has already been optimized...the only thing worth changing are the mufflers for maybe 2-3whp gain. Removing the cat results in loss of crucial low end torque for a minor gain in high end hp....plus it sounds like shit. But if you insist on doing the straight pipe...you need to plug back in the O2 sensor that was plugged into the cat.

 

There might be ways to correct it but not a simple one. What year is the car?? Regardless, you have two O2 sensors, one before the cat and one after. The one after is there to check on the functioning of the cat. What did they do with the second O2 sensor (HO2S2)?? There are small electronic devices which could be wired in to trick the ECU into thinking there HO2S2 is in place but might not work with our O2 sensor as I beleive we have wide band units.

Also, it looks like you are in CA which removing the cat is a crime (for you and whoever did the work). Don't they have visual inspection there??

Yes, the Comptech headers would work with a straight pipe, it would just need to be welded in place.

BTW, the most there is to gain is maybe 5 HP up high, not worth it IMO...

 

In California you are required to have an emissions inspection every other year to register the car. There is both a visual inspection and a measured emissions test that you have to pass.

I believe that you are correct about it being a crime to remove the catalytic converter. Not worth the pain if you get caught.

 

what the hell is that smaller muffler looking thing up by the cat? can that thing be removed? would it help performance?? i cant figure out what that is and why it would be needed when theres already 2 mufflers out the back of the car

 

Are you refering to just before the cat or after??

If you are talking about just before the only item there is the flex section. There is nothing to be gained by removing this and a something to be lost in the way of vibration and possibly a cracked manifold.

The only thing after the cat is at least five feet away towards the mufflers and that is the resonator. There may be 1 HP gained by removing it but you might get a droning sound while cruising.

 

You should be able to fashion a resistor to plug inline on the wiring from the rear O2 to give it a constant value to trick the computer into believing the cats are there and functioning properly. Now what ohm value you need to use for your car, I dunno.

FWIW, here is an example of the resistor used on my mustang (though I made my own, not the prefabbed one)...

http://www.mileliminators.com/

 

that's what i did before... and the light will just stay on... take it from me, it's not worth having a straight pipe on our car, just put it back on. i got a ticket for it and it was really painful.

i see you live in my home area, we should meet up

 

Was this a custom job, or did use use the "test Pipe" from, that guy selling them on Ebay?

 

Sorry people I've been away from the almighty computer for a couple of days. Yes it is illegal to have straight pipe in California. However, there are many ways around it. First, just bore out the cat to make it look like the cat is still there. But of course the cat becomes nothing more than piping. Thats what I did. Now I kinda regret it. To pass smog si really simple. Some mechanics in the Southern Cali area will pass your car for smog for an extra $60-$100. Anyone know where I can get a factory cat for cheap???