Loud is not always the best, one of my cars is loud, 4" exhaust with an open wastegate:
http://www.youtube.com/watch?v=FVQ0t80_AnI

The other is quiet, attracts less attention and I can drive it comfortably for more than an hour.

I have the HKS on my car I need to upload a sound clip but anyways it sounds good but at low RPM under load it sounds like a reallly big subwoofer. but I like it the tip is huge I stick my fist in it and wiggle it around. There are cheaper places to get it than 700 bucks I paid like 580 for my dragger. So if you are not wanting quiet then it is a good exhaust but I know the one Nate suggested is a really good one to and so is the nur spec.