Anybody done this? Have 2 magnaflow cats I want to install and looks like it could be slightly complicated. Lol. Seems like it should fit easily on one side but the other side is flattened out for clearance. Not really sure how I will go about welding in the cat on that side.

 

Why don't you buy the catted y-pipe from ARH, that way you'll know it fits.

 

I actually was able to buy the 1 7/8 headers and ORY NIB FOR $600 including the o2 extensions. Figured it was worth it to buy it and make it work with cats.

 

I just installed cats on an off road TSP y-pipe. It's simple to do. Just buy the cats you prefer, get two butt-style clamps, cut, voila! Keep the section of pipe that you cut out so that you can swap it back should you wish to remove the cats.