I did downpipes on my S55 M4 with the stock cat-back and it sounded amazing so I decided to try it out on the Supra. I chose the Wagner catted downpipe for it's cast turbine housing connection and it was one of the few I could confirm fit at the time. Honestly, I believe this is probably the best set-up you can do...catted with the stock cat-back. I have a catless downpipe on the car and it just sounds hollow and a bit too raspy for my taste. The power increase with the Stage 2 BM3 map and the downpipe is awesome too!