Zippy from Zippy Performance used to be one of the top tuners in the Southwest from what I here, but not too many people go to him anymore, since he's supposedly hooked on prescription meds. I also heard he blew up my procharged G8 with a N/A tune after I sold it to a local guy. Again this is all hearsay and I don't know first hand so you can decide for yourself. https://www.facebook.com/zippyperformancetuning/

I'd probably also stay away from SinCity Performance. They have a lot of parts in their store and have a dyno, but I've never seen any car come out of there running properly. I don't know them and this is just my opinion based on what the talk around Las Vegas is. http://www.sincityperformance.com/

I personally go to Frank who owns Revolution Motorsports which is near the speedway. He's a good guy, and very knowledgeable, but usually has a waiting list to get into his shop. https://www.revsc.com/

There's also Gil from HP Specialties which is also near the speedway. I've never heard anything bad about him and he just worked on and tuned my buddies CTSV. I've also been thinking about going to him for a retune, because he seems to be a great tuner. https://hpslv.com/

Garth from Leading Edge Performance (LEP) does mostly LS stuff, and seems to be a cool guy anytime I've talked to him, but over the years rumors on forums and in the streets has it that he screwed people over. However he does have some high horsepower cars coming out of his shop. You can decide for yourself. https://www.facebook.com/LeadingEdgePerformance/