If you look at the dyno charts on toomey's web page you see that at lower rpms, they dip below the stock pipe curve, but quickly out pull from 5 grand on. If your bike is stock, Toomey has the T-6 pipes that outperform the T-5 by 5 h.p. on top and through the middle..The kit is a COMPLETE kit with new jets and needles..they call it the perfect jet kit. It works. When I was running stock carbs and I bought the T-5 like 4 years ago, that jet kit was damn near perfect. Toomey wants 649 for the complete kit W/ cromed pipes..not a bad deal..EVERYTHING you need to make them work.