I love mine..they're just unruly enough to put a smile on my face without being too loud. They seem to give the car a little different sound than most of the other Mustangs I've heard.
The only issue I've noticed with mine is that they tend to collect water. I think a little drain hole somewhere would be helpful.
Installation was pretty easy. I did end up having to adjust the mid-pipes to get the tips centered in the bumper, but that was pretty easy. I definitely recommend them..can't beat the price!