Well, my catalytic converter just broke up to all sorts of pieces. And my emissions is not for another 7 months, and what with the swap and all, long story short, i'm straight piping until I can get a decent cat. now for the difficult part, i have a dynomax 2.5 inch cat back right now. But I'm sort of stuck on how to get an existing pipe to hook up to the flange on the end of the cat back. I was thinking about cutting of the end of the cat and having someone weld that to a piece of exhaust pipe, but, i'd like to stay away from welding if possible. I could also hollow out the cat, and just put that back in, BUT, i had to cut the cat away from the header exhaust pipe, because of the heat the cat welded itself to the pipe. HELP!

 

The stock "I" TENDS TO BE 2.25
THAT SAID
I used a 3.4 CC from a 1995 3.4 F Body & it fit perfect my 1985 pipe set up.
And the 3.4 CC is 2 1/2" in & out.
TO ME the previous owner had some work done & I benefited from it.
That said, find a muffler shop and have a "universal" CC installed.
Because that seems like the MOST SECURE set up you can attain.
OR do order the headers for the reason that the Pace Setter Exhaust headers includes a new "Y" pipe that is "Stock" including the ball flanged end at "Y" pipe, prior to the "CC".
THEN you only need be concerned about the end to the "I" pipe, as (with Pace Seter Exhaust purchase) header & the other pipes will be all brand new.
EITHER WAY you are spending money to solve the problem.
What's wiser investment?