Not sure ive heard it does great on acceleration my buddy whos ski is bored, ported, hi comp head, the flywheel dual 42's, pipe, waterbox ,prop all the imaginable wingdings possible to a 550 he did it flew like a bat out of hell but his coupler cover was missing and no bilges so the carbs got too wet and gunky from the moisture and the bottom end was crap to nothing so top end its seems really good but the most important part i wasnt able to tell. i couldnt imagine a product being 525 wouldnt work to what they say it would.