We won't mention how the guys truck I helped with shift. Friggen thing was lifted on 37's with 4.88 gears, and would bark the tires locking up. Had the converter set so it was basically on or off.Had bad luck with Justin @ blackbear when he tuned my 01 5.3 and dad's 04 5.3. Got shit mileage and the trans shifted awful. The 01 was totaled and the 04 is still driving with it getting 14 mpg and harsh shifts