Go to the search feature and you can get all kinds of sound clips - borla, tubi, awe, fabspeed, etc. One quick link for borla is http://www.youtube.com/user/dwm4p If you watch/listen to enough of these you will find that the different drivers make a hell of a difference; nothing is going to sound very good with slow/sloppy shifts at 2500 RPM.

I put a borla system on my 97 viper a few years ago and found it perfect. Really sounds great with the lower reving big block. However, the two 911s with the borla set up that I've heard live left me ho-hum; nice but pretty mild and similar to pse. On my 911 I was between awe and fabspeed and chose the latter because at the time of purchase I got a much better deal; I don't know what today's prices are. If you are going to flash it for the performance benefits I hope you'll do a good airbox also.