I have a 03 2.7L GT Tib, with a Greddy Evo 2 catback exhaust system and stock headers. If I remove the catalyc converter and leave it straight pipe, is it going to give me any weird noises, or any horse power? what do you guys think?

Dear cruz,

First off, how do you plan to pass the California Air Regulatory Board test? Second, modern catalytic converters are designed to have no more than 1 psi back pressure when measured. The benefit of removing the cat from a car for street use is widely over-estimated. Third, how are you going to regulate your fuel mapping? As soon as you remove the cat, your last O2 sensor will send a fault and your ECU will revert to factory default open cycle. This tends to run rich at idle and subject to lean out at high rpm.

So, minimal horsepower gain, slight noise increase, but plenty of check engine lights and your ECU reverts to open cycle fuel map profile.

Byron

You're in Cali, so don't even think of taking it off and passing emissions tests. Besides, like byron said it's not going to make any noticeable difference in power anyway, so why mess with it??

If you want a more aggressive sound and a power boost go get yourself an intake (I have the Injen SRI and it's great).

I have a Injen sri too.

Dude, i took my second cat off and i don't have a problem. But then again i have the I4 and there is an o2 sensor before the first cat and after the first cat so that may make a difference cuz i don't have a 3rd 02 sensor. Does the six have Three of them? cuz my APEXi exhaust is for the four and the six and there is a bung for a third 02 sensor, with a screw in plug there.