I ran straight pipes on a 5.0 litre Mustang back in the day. It was quite loud with lots of backfiring and gurgling upon deceleration. It was obnoxious. Not quite what I would recommend for an M5 which is 100 times smoother/classier. Its a cheap solution if you are just looking for loudness though. Just my $.02.hmmm
Yea i figured that,i will probably keep some sort of cats on the car.Would the supersprint cats be necessary? Or could i just get the hi-flow cats and have them welded in? I cant justify spending that much on those SS cats though,thats a bit much.