I have a 98 Valkyrie , put a set of cobra 6 into 6, removed the baffles, and put a k&n air filter, call theses guys told them what I had done and the sent me the kit, my mechanic looked at it and scratched his head... 2 sizes up on the small jets, 2 extra washers on the needles, and 7 sizes up on the mains, went from 100 stock to 115's on the main jets, he questioned me was I sure this was right???? I told him I had called and talked to them in person, and they said this was what I needed, put them in, about 4 hours later we fired it up, sat and idled smoother than before I did any changes, we looked at each other and just smiled, now the real test, down the road about 6 miles letting it warm up, turned around and WOW!!!!' hang on !!! I don't know how it could have been any better, no hesitation, no stumbling, just steady PULL!!! We put 260 miles on yesterday, run fine under (normal driving conditions) my mechanism said he would never have believed that it ran ok on the stock jets, and we could go from 100's to 115's and it not be too rich, but I think they were on the money, don't question what they send you, just put them in and smile when you twist that throttle!!!!!!