I'm sure hull design plays a part as well. A friend of mine has an Eliminator that had a decently built and fresh 460. It topped out at about 65.6 mph with more throttle left just wouldn't go any faster. Now it's got a (I keep forgetting) 510 Ford built to the roof , shoe, ride plate, stuffer, loader, droop, etc. but he wouldn't gps it last time we were out in it. ? . He just bought a second jet boat, a California Performance Gull Wing that supposedly did ? 118 ? mph a several years ago. It just needs a refreshining and I'm sure he will gps that one, without me in it.