What does the car have done to it now? If it is all stock then don't bother with a "chip" or any of the other reprogramming devices. Best way to gain HP is not with a "chip". First add a direct flow air lid, then swap out MAF ends. Get rid of the paper filter and get a K&N or equivilent. After that add a good catback exhaust system to let the car breath. I know for a fact that this will take you from about 285 at the rear tires to 300 to 310 at the wheels. The intake tract on the LS1 Fbody is a monster of a design. I belive it is purposely made to restrict the incoming air to the motor to keep the HP from being the same as the LS1 Corvette. The Restrictive stock exhuast needs to go and you need to open the intake tract up before you start looking at tuning.