I had a B&B installed about two months ago on my '99. I really like it and it gave me a small boost in hp. Not a bad price at all, about $1100 with shipping and installation.
http://www.986forum.com/forums/showthread.php?threadid=497
The Gemballa is the best I guess, but too expensive for me.
Now some people say the B&B doesn't have the right sound, but I think it sounds great. Throaty and not "tinny" like someone said. For the price I don't think you would be disappointed.