The short of it is I have a 2002 RS, 3.8L V6. It has an aftermarket exhaust that's larger than the stock 2.25-2.5" diameter. I need to put a CARB certified CAT on it for Colorado emissions. The CARB cats are all sized at 2.25-2.5" diameter.

Am I going to ruin anything if I have a welder taper the exhaust pipe down to fit the smaller diameter of the cat?

The background is my dad bought the car new in 2002, he's passing it down to my son to drive as his first car (pretty cool right?). Well we live in Colorado and follow the CARB emissions standards. The cat on the car right now is bad and must be replaced. A new cat should get me through emissions.

BUT years ago, I don't know exactly when, my dad had a larger aftermarket exhaust installed on the Camaro. The diameter of this exhaust and cat is over 3". The catalytic converters that are certified for this Camaro are all 2.5" or 2.25". I have a good fab guy that can taper things down to fit the new cat. I just don't want to do something to damage the car by tapering the exhaust down to fit the cat.

TIA!

 

anything over 3 inch is to big. he may have done it to lessen the exhaust rasp. have no idea if it works. you will not harm engine going smaller, performance and or sound may be effected. you might look at v8 cats to see if they at least go closer to 3 inch. there are aftermarket cats that are 3 inch but dont know if they are legal in your state.