The power achieved by motors like the Hyabusa's has a lot to do with the maximum rpm they can turn. If you can fill, compress, ignite and expel the gasses more times in any given period ( the PM in RPM ) the more power you can produce in that given period. Our engines redline at somewhere around 7 grand, the Hyabusa engine can spin comfortably to over 12 thousand, therefor making almost twice the power in the same amount of time. They also have considerably higher compression ratios, somewhere in the neighborhood of 12 to 1, as opposed to the 16v engines in the Trackicks which are at 9.5 to 1, or the 8 valve Sammy and earlier Trackick engines which are closer to 8 to 1. The more mixture you can put into the cylinder and the more you can compress that mixture, the greater the pressure created by the ignition of the mixture. This is a very simplified explanation and I'm sure there are others here who can do a better job of explaining the differences.
