I just bought some Mac mid length headers today with the ORY and now need some cats to weld on to it. Was considering RT bullet cats for 260 shipped for the pair or some magnaflow cats at about 200 shipped for the pair but I don't know which size would fit with no clearance problems. Y-pipe is 2.5in. Hopefully someone on here has done this already for some advice.

Also would the chrome finish that is coming on the header be any better than nothing?

I'm shooting for 375rwhp through my a4 after the install of everything.

 

what size collectors? I used to run a magnaflow cat, it was pretty good. I would use one again if i was going to run one.