Like the others said, try using it right out of the box. If you want to try to adjust the shift points, go 2 turns at a time and see how it runs. The performance will also depend on what you have done to the transmission and engine. On my old 289 w/ C4 and no shift kit, tightening up the modulator worked pretty well, and I was able to get crisper shifts out of it. With the new 331, and a rebuilt C4 with shift kit, tightening the modulator didn't seem to help, in fact, i thought it made it worse. The tranny didn't shift at higher rpm, but it seemed to make it more of a clunky type shift and it took longer. When I backed the modulator it shifted quicker and cleaner.