Which M3 exhaust should I buy that will reduce the most backpressure?

I'm hoping to soon be getting an M3, and I've been looking at alot of different mods and such. I've got my mind set on a number of things from Dinan Stage 3 suspension (*Flame Suit On*) to a Vorsteiner CSL decklid. What I can't figure out is which exhaust to go with. I've looked into Dinan, and I'm seriously considering Dinan since their exhaust reduces approximately 82% of the backpressure created by the stock exhaust system. From what I understand, many after-market exhausts still have alot of backpressure.

Are there any exhausts out there that seriously eliminate as much backpressure as Dinan? Which ones should I look into?

Also, I tried searching for it, and can't find any posts that have sound or video links for the Dinan exhaust. DOES ANYONE HAVE A LINK TO THE SOUNDS OF A DINAN EXHAUST? Or, Does anyone have a Dinan exhaust and how does it sound? I want something with little to no rasp and something that's throaty and rumbles a little bit to let people know I'm there when I'm idling at a light, but nothing terribly loud or obnoxious.