I have set to 91 (highest I can get here). Like others have commented, i don?t notice much difference in comfort; however, in sport the torque increase is impressive - especially at 60+ mph. Hard to quantify exactly how much with the butt dyno. It was definitely worth the expense. My better half also has a GT and she can feel the difference. I bought that OCC, but haven?t installed it yet. I did some recon yesterday to figure it out. I noticed there was a one way valve and stared wondering if it?s even necessary.