I understand there is a tool Lingenfelter makes in order to unlock the factory limit. I read it in GMHTP I think. I think that was ADM's 'V pulley, intake, tuning article.
If you go to a reputable shop, like one of our Sponsors, you'll be just fine. You get what you pay for, though. I definately wouldn't go anywhere that doesn't do a lot of tuning on your specific car.
"...What IS true: We anticipated that this would happen - we are never finished - and yes, Ford DOES deserve to win now and then. To think that GM can come out with a car to make ford throw in the towel is simply foolhardy..." - fbodfather