I have a loud aftermarket exhaust that sounds like I am in the fast and furious, it was on the car when I purchased. Really annoying. I need a more aggressive low sound.

Any suggestions

Any idea what is on it now?

The usual inexpensive route is Magnaflow rear mufflers with or without the center resonator.
With is rumbly and without is louder.

The expensive route is Eisenmann which is a European resonator back system at a couple of different sound levels.

Sound clips are attached to this post: http://bimmer.roadfly.com/bmw/forums/e31/7913513-1.html

The original sound post with pictures of the recording setup

http://bimmer.roadfly.com/bmw/forums/e31/7912837-1.html

I have the Magnaflows on mine and it sounds great.