What are some simple mods i can do my self to improve efficiency/performance? I do know that bolting on a diverter should help. But the wallet says its gonna have to wait. I need to replace the rear bushing soon so i plan to do what i can at that time, including a new wear ring. Its in a 20.5 mini cruiser w a mild 454. I'm not sure of top speed because speedo shows 30 at 4900. I know it was going faster than 30. But it does feel like a little slipping out of the hole. But both 26 gallon tanks were full and 6 people were in it. Top speed "feels" 50ish.

Have the impeller detailed.
Smooth the transition between the intake and suction housing. (kind of a sloppy fit)
Detail the suction housing and intake down to 220 grit.
Remove every other bar in the intake rock grate, and sharpen the ones that remain, both sides.
Wear ring is a must...along with setting up the front to rear tolerances by shimming the bearing.
Detail the leading and trailing edges of the bowl.

An inducer would be nice, as well as a diverter. $$$
Shoe and rideplate...$$$ especially on a larger boat.

A WJ will support as much HP as you can throw at it.
A WJ already has a 17-4 shaft, unlike a stock Berk and clones.

4900 with a 330 hp 454...that pump needs some attention.

Dan'l