Yea I ran one on a 440 last year. Made a big difference on low end letting the motor rev up but the price of them is too much IMO. I am putting on a jetinetics total loss system on a 550 build this weekend that didnt cost much more then what some people are paying for the jetinetics flywheel. I bought the whole kit for $175 and had Jet Ski Solutions rebuild it and set it up for me for $300. Should have a lot more bottom end then just a lightweight flywheel but we will see.