I wasn't aware of the 2 stage springs, I will have to see if I can find some. As for the 40 mm carbs, I have read that alot of ppl have switched out the 38's. Will 40's make a huge difference? I do have a set off a '90 Wildcat Mountain Cat I got as a parts machine. If so, I would presume that I would set them to the specs from 1990 as far as jetting and such?