Thanks for all the input everyone.
There's so many good exhausts out there, now I just need to go hear them for myself. At least now I have a better direction though. I'm still leaning Eisenmann Race I think; just love the sound of that thing.
2009 E90 Le Mans Blue M3 6MT De-Chromed, AiB V3, Rogue SSK, Brembo BBK, Eibach Pro Kit, Eisenmann Race Black, ESS Tune, MS Filter. 1998.5 Titanium Silver E36 M3 Coupe NASA GTS2 Race Car.