Looking for some guidance. I have a 2008 Porsche Design Donzi 28'. It has a Mercury EFI 525 with a Bravo 1, 28 pitch prop. Its slow coming out of the hole and tops out at 70 mph when running really light 9should get to 80 mph. Would like some advice on whether the whipple supercharger would be a good fit or if I can get acceleration to plane improved along with top end with a different prop. I appreciate the input!

Need more details, such as what is your wide open max RPM and how much does that boat weigh? Where is the trim and tabs set at? I'm not sure if the bottom and weight is similar to a Donzi 28 ZX, but if it is you probably are close on max speed with a 525. And that 28 pitch prop might be too much, lots of variables here with a not too common boat.

Not sure on the weight. I'm at 5400 RPM with tabs all the way up and trim at optimal spot for speed (definitely a bit of a rooster tail at optimum trim for max mph)

Did a quick look and found one with a 600sci that claimed 80.

Shouldn't 5400 with a 28 be faster than 70?

Maybe too much trim?

My 2000 formula 382 with 500EFIs has hit 76 GPS (cold day, very light fuel load) with non-labbed 28 pitch Bravo 1 props at 5200 RPM. Seems like something isnt right with 70mph at 5400. 382 is a very heavy boat.