A tune today means that we re-write the operating program parameters in the ECM (Engine Control Module) or the TCM (Transmission Control Module ) .
These parameters like spark ,fuel/air mixture and maf frequencey & Torque Mangament to name a few, are all accessed using tuning software such as EFi LIve or HP Tuners .
These tuning software package work via the VIN ,reading each cars parameters in order to change them to improve performance and gas mileage .
Hope that helps a little bit
I don't think Les (AGVI) ment and disrespect , being around Corvettes and Corvette people all the time like Les is , would leave the impression that everyone must know about how Corvettes are tuned these days .