I finally got around to messing with the setup on my Crestliner VT-18. I haven't moved my engine height any at all, still in the 2nd hole down. Had a 19P Spitfire aluminum prop from the factory. I could get 40mph or so top speed before blowing out the prop and that was straight line only. Boat speed stopped increasing after about 5300 RPMs. I took the boat to have the motor raised and had an interesting talk with the owner of the shop. He noticed the paint was chipping off my prop, said that was the first sign of cavitation and the paint was actually being burned off and that he wouldn't recommend moving the engine any higher with that prop. He recommended a stainless steel prop in the same pitch. I ordered a Turning Point Express Mach4 19P 4 blade prop to try. The difference was amazing as soon as I took off. The hole shot was much better (not that it was bad before) and the top speed increased to 45-46 depending on chop and wind. Before the prop change I could get 40-41 mph in a straight line, but you could forget turning as the prop would blow out almost immediately. Now I can trim the engine to run 6K RPMs and actually drive the boat without worry. I'm not sure I'll raise the engine as it performs pretty good where it is. I might consult the shop owner again to get his thoughts on raising the engine. So far, this guy has been spot on in his advice on everything I took him. I know alot of RT188 and VT-18 guys are running Laser IIs and Spitfire X7s, but this Turning Point Express is pretty good for less coin. I've got $350 for the prop and hub kit in it and couldn't find a Laser or X7 for less than $425 new shipped.