OMC 115 Turbojet sluggish?

[MTBoat]

I have a 95 turbojet with OMC 115. It runs within most suggested behaviors, has pretty solid snap our of the hole, and yet seems a bit underpowered once it hits the higher rpms, topping out at 4400 rpm and ( I need to take a gps along next time) seems about 25-30mph. I love the whaler boat, and it goes anywhere, but, wondering if my advance timing is off or it the powerhead is a little tired at an exactly even 103 compression on all 4?
Anybody have experience with these motors or some ideas what might spice it up, or what is expected in terms of top speed and rpms for the 95 15ft BW configuration.Thanks...

 

[boobie]

Do a good de-carb on the motor and see what happens.

 

[MTBoat]

Is there a best "recipe" for decarbing? I have heard many formulas, but would like to employ the procedure that works best with the ideal products...

 

[racerone]

It should run at about 5500 RPM.----Check for spark on all 4 cylinders that will jump a gap of 7/16" or more.------Last one I rebuilt had broken piston rings and 5 high speed jets installed instead of the proper 4 jets.---No idea how someone would install an extra.