exhausts aren't really going to have a HUGE sound difference. They all sound good if you go with a name brand, and basically do the same thing(give the same gains which are not extremely noticeable). I have the UUC complete exhaust for my car and it is loud!!, but I've heard that other exhausts like AA are loud as well. i also have 2.5" piping and no cats at all. It's mainly personal opinion really. find something you like the look of especially.
FOUNDER of the BMW-Forums Michigan Club
<span style='color:green'><a href='http://www.cardomain.com/memberpage/458339' target='_blank'> Car Domain UNFINISHED </a> </span>
<img src='http://www.bmw-forums.com/forum/uploads/post-4-1078289877.jpg' border='0' alt='user posted image' />