Anyone care to explain why a tune is not necessary? I put SLP long tubes on my GTO along with a cold air kit and had it dyno tuned afterwards. The car was loud before the tune... After 6 pulls and a drive with the lap top hooked up, it was more quiet and I gained about 20 HP. The tune helped lean the fuel mixture across the RPM band and tied all of the mods together to get the most out of them. I would assume that a GTP with headers or some other manifold mod, air filter replacement, and down pipe replacement would benefit from a tune of some sort, similar to any other car. Maybe a tune is not required, but very beneficial?
