I agree that sound plays a tremendous role. I read good things on the Eisenmann and Supersprint Powerloops, but that price is impossible to justify. However, the drone of the Diablos (and RPI's) from what I hear is too much for me.
Anyone try modifying the E46 M3 Corsa system (
http://www.corsaperf.com/product_dis...px?product=663) for the Z4M? Is it a full pipe/can configuration or just axle back cans?
There are some good videos with an E46 M3 and they sound great: