Socal,
Most M3 owner would just drop $2k, because M3 owner can, on a system and be done with it.
My exhaust is pretty much straight through but it is too loud. I didn't think it was gonna be loud since my 2000 M Coupe had a similar system and it was not even close to being loud. My resonators are out and after market muffler that resemble BB Triflow design. From 1500-2500 is drone like crazy. Beyond 2500 rpm, it sounds like a V8 race car. Beside the loudness, my whole system cost me $320.00 (parts and out source labor.)
I think I am going to wait to hear how your sounds and probably going to do something similar.