GenVibe - Community for Pontiac Vibe Enthusiasts

I talked with a guys who's into mecanics at my gym, and he told me if I don't change the cat at the same time the cat back, the gain will be less than what it can be. The limit will be the tightess place on the the engine. If the end of the headers is 2 inches, a 2.5 inches cat back won't work at its max capacities... So my question is, should I buy a new cat at the same time that my cat back, or you think the original one will do the job cause it's already a good and /or 2.5 inches cat?

Well a bigger diameter cat would obviously help, but man what a $$$$!

If I am not mistaken I believe that legally a mechanic can not install a new cat unless the old one is deffective or has like 50,000 miles on it. A friend of mine just got a highflow installed on his truck, and after a little persuasion he got the Midas people to do it. And if all else fails a hammer and a metal punch should do the trick.