Mike,
I was in the same boat as you, what i ended up doing was buying 2 upgraded M3 Euro tip from this website
http://www.eurosportdesign.com/ps-25...aust-tips.aspx
I received them last month, and the quality is outstanding. I haven't yet had a chance to install them. I really did not want to go the route of installing any type of muffle(magnaflow, flowmaster, remus etc...) because
1) I did not want to spend a heap of money on a mod which really wont add any hp (more for visual appeal than anything else)
2) I didn't want anything which would sound like a honda w/ a fart can
3) $$ money again, I didn't want to spend $900+ on an eisenman
So what I plan to do is have these welded to the factory exhaust... At least that way, I know it's not going to be crazy loud or obnoxious.
Good luck to you,
Dan