I was out playing around with the jetting today. It has a 13.5:1 head, crankshop twin pipes and k&n filters. Unfortunatly no egts, but I ended up going 620's on the main jets with absolutley no engine studder or excess fuel loading. Judging by the plugs I could have went up another size. This testing is at 2500ft. Does anyone else have any experience with this same setup. I am still having a hard time believing that it needs 620's. I should say that I had detonation with 580's. Thanks for any input!!