You need to get to know M5 a little better. Above 4000rpm M5 is much, much faster. I used to have 535 5 speed. Mine (M5) is faster than my neighbours new G35 and pulled away from 2001 corvette on sunset at palisades. Dont know any non turbo car that will be faster than M5. '90 535 5 speed with JC chip was not faster that V8 mustang.
Mike
'91 M5 Dinan chip ( http://www.cardomain.com/memberpage/186441 )