I'm having my friend Donny in Leesville price out a pair of Magnaflow #12589 mufflers for my upcoming exhaust system. They are 5"x11" body, 3" inlet and outlet. I plan on running 3" from behind the cats and possibly an X pipe as well. It will be tricky plumbing the tips to this size pipe but I've done harder stuff than this. If there isn't any benefit from this system, I'll put my 2-1/2" system back on.