The only true custom tune, is a custom dyno tune for your vehicle. Anything else is just a canned tune, Mike SCT Tuner.
Not necessarily Mike, you could have a custom programmer out of state e-mail you a tune for the current Mods on the car, then you'd make Dyno runs and Datalog specific parameters, send them back for review and then a Final revision will be made taking those numbers and A/F readings as a guide!:bigthumbsup
Custom Dyno Tune- up to $500
The method I described.. $125 if you already have a Predator or SCT hand held to import the Tune!
A Custom Dyno tune will give you the most part throttle response and peak HP but the method me and many friends use is the latter!
The guy tweaking behind the laptop is Very Important as well, that's a Given!