I love mine. I combo'd mine with Headers and Downpipe from
www.badnewsracing.net as well as a Trifecta tune and Injen intake. I recommend getting a tune first, then building from there, otherwise all you'll be getting is sound difference. The Injen intake I got a killer deal on, and it sounds great, and I did notice the power increase, but DDMWorks would be the best route to go.
Anyways, ZZP is hands down great quality and sound for the price. I also got the Test Pipe with mine. I would get a Test Pipe + Muffler, that's the setup I run on the ZZP System. I started with Test Pipe + Muffler Delete option but it was too loud. If you have emission laws in AZ then get a high-flow cat instead of test pipe.
Good luck! - PS, it's all bolt on too, very easy to install. You do need to cut the stock exhaust off, unless you want to drop the axle which is something I didn't do.