Turbo Tune would be my pick also,
John Keen has leagues of experience on any of the other tuners mentioned above.
-He has built and tuned V8 super cars for the last ten 10 years.
-He will happily provide warrenty on the Cars he Dyno tunes!!( I don't know a single other tuner who will back up there work like that)
-The Dyno he uses is the newest and most accuate hands down in Adelaide(2WD + 4WD) It has sperate cell correction which means that no matter the temp or realative humidity you will always get the same power reading.
Yes other tuners might get more power from your car however how long it will last is another story, and when it does go bang.....do you think they will say" no prob, it's under warrenty"