What prop are you running.
 

I have a 98 donzi 22zx 454 310 hp. bravo 1 1.5 gear. what pitch prop are you runing.

22ZX prop
 

My 1999 22ZX came with the Bravo I 24P four blade - boat ran 64mph on the speedo.

I had a 98 with the same engine and it was a 22 pitch before I supercharged her and beefed up the engine.

1999 Donzi
 

My 1999 Donzi 22ZX came with the 454mpi 310 hp engine also called the L-29 my Mercury - this engine was equipped with a Bravo I 24P from the factory. Boat ran 64mph on the speedo.

I pulled the L-29 and replaced it with a 502MAG MPI which uses Bravo I 26P when built this way by Donzi. Boat ran 72GPS 74mph speedo.

Switched to ported and polished cylinder heads with the inconel valves and Crane rocker arms pushrods and Comp Cams valve springs. Installed CMI E-top stainless headers, and Vortec air filter on the intake. My Donzi likes both Bravo I 28P and Bravo i 30P props and runs 79mph GPS 84mph on the speedo.

What rpms were ya'll running on the 310 hp??? is the range to 4800?

Bigmac had a 24b1 and now he is trying at 21rev4.. 4400 wot and now 4800 wot respectively??