I have one in a bike I built with a Comet 94c/90d (stock spring rates) and added a 90CAM-280-0211 Camshaft, 280 0211, GX390 (Approx .280 lift and 220 duration (at .050)) from NRracing, 50lbs springs along with the campion shaft mounted rocker arms and new pushrods. Mine will do ~4700 off the line and at top speed its ~4100 @ 60 mph. Pretty good deal and power for the money as is, I was just looking for more low end torque is why I added the new cam, etc...