I want to convert my 97 dual-cat car into a 95-96 single-cat car using the MAC mid-length headers and y-pipe. I know I will need felpro header gaskets and a high-flow cat. Seeing as how the MAC y-pipe is 2.5" and my Borla cat-back is 3", I will need a 2.5" in/3" out cat.

What will be needed to connect the single-cat y-pipe to my cat-back? Just some bending?

I want to get locking header bolts so that I don't have to worry about them coming loose.

What are the other things I will need to install these headers? Will I need O2 extensions? If so, what kind, and where to get them?

 

bump

 

For starters, search, youve been around long enough to know this subject comes up twice a day.

Second, if im not mistaking, the mac y pipe, is 2.5" on the y's but comes together to a 3" peice where it connects to the i pipe. not positive on that though

 

A 3 inch cat will work. That is what I'm running with my Mac's into a 3inch I pipe.

To connect the i pipe to the single cat y pipe youll need a "s pipe". An exhaust shop may be able to fabricate one for you. If youre bent on doing it on your own, SLP sells a S pipe, but its a bit pricey.

edit- i would do a "mac header" search under the username "stereomandan" he did the exact conversion you did a few years back and documented everything pretty well.