Scott Schneider aka "Motorhead" is in California, he has done pretty well by me. He's also a national class FT shooter. If you're looking for work on an FT gun, can't think of anyone better.
I've never dealt with him, but another guy named Will Piatt seems to be legendary with the Sam Yang guns.
I have a friend who used "John in PA" for a springer tune and was quite satisfied. His is another name that comes up a lot in discussion of trusted tuners. I don't know his full name, but I think he has a presence on GTA.
Allen (?) Zasadeny is another guy who is kind of an industry legend...and another guy I haven't dealt with personally. Others might know how to get in contact with him.
David Slade at airgunwerks.com - I think he used to be "the" tech guy at Theoben and is another industry legend.