QUOTE (akkeith @ Nov 1 2009, 07:30 PM)

Why do they do that? You would think they would want the best performance right from the factory. Any warranty problems with performance tunes? Thanks
They do it because they give you a 100k power train warranty. Aggressive torque management programming prevents sudden loading of the power train and reduces stresses on the driveline and transmission, as well as axles in general.
Your 100k warranty may be null and void if you get a custom tune and a major component in the powertrain breaks.