Its a design element of the C4. Basically the way the planetaries and bands are operated, it disengages 2nd before applying 3rd. This causes the engine to flare between the 2-3 shift. On high HP cars, once 3rd is engaged, its possible that the motor will burn up high gear because its at a higher RPM than the tranny. Think of it as dragging the clutch every time you shift into high gear. High gear is tough on any auto because of the loads, and the way the C4 shifts isn't any better. Because its inherent in the way the tranny is designed, it can't be overcome.