2008 Porsche 911 Carrera or 2008 BMW 650 or M6?
 

Check out almost any Mercedes AMG instead. They beat the M out of the water (forget the 650). BMWs are fickle machines with unappealing interiors and flashy exteriors. At least the Porsche is designed for one purpose: pure acceleration. You Vag com 15.7 sacrifice some things for that (as you are well acquainted with the ride stiffness, I'm sure) but you get a car that has its place and that's that. The BMW leaves a lot to be desired.

What I mean is simply this: keep the Porsche, enjoy that growl, and don't bother with the BMW. They're so common.