I have been involved in martial arts a long time, and currently am an instructor in my own right. My quote to the owner of Sitan Gym after my first class was "I've been walking around thinking I'm pretty good for years... then i came here." Their fitness preparation and conditioning blew away anything I had done previously.
Their instruction is top notch and they are verifiably legit as their fighters compete often, and often win. I am very proud to be able to say I trained there for a short time.
If you want to learn straight-up Muay Thai in Arizona, this is the place to go.