running 33's with 4.1 ratios. trial and error the first time only moved it a small amount anti clockwise and went out further so i went the other way a touch and got it spot on. had the car strapped on a hoist with rear whells off the ground, with my car 100kph by gps in 5th gear it was doing 2100rpm, while car was running i put in 5th gear then wound the idle up until it sat on 2200 and set the speedo at that. dont recomend you try this at home can be a bit of a danger on jack stands