just to let you guys know what worked for me. I live at 1,700 ft above sea level and with the white brothers slip on and the k&n drop in I run a 157.5 main jet and I tried it with the neadle up a notch, (ran like crap). tried it with the 157.5 and the neadle in the stock position. wow! thats what this thing needed. if you live closer to sea level you'll need to go richer, if you live higher than 1,700 you'll wanna be leaner. but only drasticaly if there is a real big change in altitude. 1,000 ft give or take may be the same as mine.