I have a 94 - 29 footer, I currently have the motor out of the boat do to poor running at the end of the season. I am debating increasing the horsepower from stock 415 to somewhere between 515-550. the boat currently ran 62mph in perfect conditions, was wondering if its worth the extra money to increase the power am I gonna see that much of a difference in top end? I know I will need to change the prop I am currently running a 22p 4 blade, also not sure what size prop i should be looking for. thanks.

I've always heard 20hp for 1 mph.

I would say probably not worth it depending on extra cost.

Depends on what your currently spinning your prop. For example, say your spinning your 22p at 47-4800 with current power and plan on 5-6 mph increase which would be now spinning at 50-5100. Your cruise didnt change b/c you couldnt change prop pitch. Then in IMHO, not worth it.. again depending on extra cost.

Even if you can increase pitch to say, 24p, then you only gained maybe 2-3 mph at same cruise rpm and top end will still only be 5-6 mph at lower rpm as you will lose 400 rpms with the additional 2" in pitch added.

teclpse,
There is a lot of knowledge on this sight ,,,, Look for Proven Knowledge or "I Have Done This",,,,,, not "I think" "in my opinion" "if it were me".
A lot of us have spent money, blown money, and sometimes get lucky and Find Some HP/TQ/Speed with our changes,,, be it "WANT more" or "Have to and decide to upgrade"
Then you can pick the Best Knowledge that fits your plan ,,,,, ask questions for Details