I've lived in Vegas for all of my life, and I've yet to find a reputable mechanic. I've been taking my
stang to Auto Tech at Craig and Decatur recently, and they've seemed to do an alright job. They make sure all your fluids and everything are topped off and they're pretty thorough. Nothing I would 100% guarantee though, because I haven't had enough work done there.
I'm also looking for a good muffler shop in the valley besides "Best Muffler Shop". If anyone has any suggestions, I'd appreciate it.