Im planning on purchasing a 3" cat-back system soon and this question just dawned on me. If the stock exhaust system is 2.5" inches, will changing to a 3" inch cat-back back cause fitting problems on a stock 2.5" cat?

thanks ran

 

It will fit just fine.

 

?? Are you sure about that. 3", and 2.5" where do you suppose that will work. Is the exhuast full 3" across, is it street legal, what is OD of the Cat? I think if it is street legal, it will. They usually come with a tapered end so that it will fit smaller fittings.

 

I ran the Vishnu 3" catback with factory cat prior to installing 3" DP and hi-flo cat. Cat-back is not tapered but there is just enough surfance area where the 2.5" factory cat flange joins the 3" cat-back flange to allow them to seal.

 

The AMS Cat Back has a collector that is 2.5" at one end and 3" at the other. Every thing comes together just fine.

 

I have the 3' RMR DP and Cat back and it's fine with the stock cat.

 

thanks to all those who replied!!!
-ran

 

Our exhaust, the SCCA legal version, is designed to fit to the stock cat also. It uses a bellmouthed piece that necks down to 2.5 inches. This piece can be removed later and you can add our 3" downpipe or offroad pipe to the system. The nice thing about this is you don't end up with a 2.5" restriction in the middle of your full 3" exhaust system.

David Buschur
www.buschurracing.com