When I went to see Lidio for my tune last spring he had mentioned that the 20" wheels and the 4:10 gears would show less RWHP numbers but I didn't care as long as the numbers were there on the time slip is all that matters. My last tune was done on the street only it didn't even go near a dyno, that's the future my friends and it's here plus the 6R80 and 10R80 can only be tuned on the street..