My 2 1/4 inch exhaust with sport muffler. I first bought the muffler (Noname brand, bought mostly for looks) then had a shop custom fabricate a 2 1/4" pipe from my gutted cat to muffler. Muffler was $100 and 2 1/4" piping was another $100. The pipe is stainless steel and inlet to muffler has same 2 1/4" diameter. Exhaust sound was very nice and deep, not ricey at all. No noticable low-end power loss and much nicer high-end reving. Next thing to get is a DT header (or exact copy) and 2 1/4" piping up to the header. I'll try to get a sound clip, but not sure when.