2+ on GSS - http://www.gssspeedshop.com/Home
Joe, AJ and the gang at PST guys are great but not exactly North Dallas
Not North Dallas, but they have a race track in the back yard to test on. When you pick up your car you'll know its done, running, and set-up correctly. With all the others you are going to end up towing to the track to test anyway, seems like PST would actually save time vs. having service done in the metroplex at a facility that can't test their work.
Not saying these other shops aren't good, I am sure they are, just that they have limitations given their location. My older 911 is mostly serviced at Mayo's in Euless and its a pain because after every service I still have to go back to the track and my mechanic still has to make a house call while I am there testing. My 996 is serviced by both PST and TOPP Racing at the track and the logistics are infinately better.