[Gerry Zagorski]

Something is not making sense here.. You said before you took it to have it looked at you were making 6000 rpms and going 19 mph and when you got it back you were making 6000 rpm and making 24 mph... If your rpms are reading correctly, and you have it on the same boat, the only way that would be possible is if they did something with the props since 6000 rpms with the same prop/same boat should give you the same mph. Did they change the prop or perhaps re hub it?

And, it looks like the Wide Open Throttle rating for this particular engine is 5800- 6400 rpms, since you are in that range, that would indicate that the engine is performing as it should. If there was something wrong with the engine it you wouldn't be able to achieve those RPMS..

Need more info here. something is not adding up....