I need to get my car through inspection and I don't have the money right now to replace my 2.5" high flow cat with a 3" unit. My I-pipe is rotted to hell and I've already bought a Dynomax 3" pipe to replace it. Is there anything out there to adapt the 2.5" cat to the 3" opening of the pipe? Keep in mind, the pipe has a flared opening and so does the cat on there now so I have to make it work somehow. It'll cost me about $65 at an exhaust shop to get this done but I'd rather do it myself and save the money.

 

I'm sure an exhaust shop could fab you up something.

 

If you can weld, or have a friend that can, you could do this. Get a 3" to 2.5" reducer from most auto parts stores, and weld the 2.5" end onto the flange of the cat, that is if you're not planning on keeping it after you take it off. Otherwise, you would have to find some scrap metal to make into a flange, and then weld the reducer on that way you can bolt it onto your cat instead of welding. Of course that might not be worth your time in which case you'll have to get an exhaust shop to weld something up.