Welcome fellow Phoenix member!
As far as Pitstop performance, haven't heard of them...
The two shops we have here that are very good are Vivid Racing and Intense Motorsports. I've personally dealt with both and recommend either one. Awesome people, good service all around.
If you're in the market for exhausts, and come across Agency Power and like that, they are made at Vivid and are one of their signature products.
If all you're doing is a HFC/Exhaust install, you could really do that yourself if you have a couple of jack stands and a free Saturday. It's really quick. Saves a lot in labor costs.