I had a good friend who's a pretty solid mechanic (though not really an outboard motor mechanic) on the lake with me and he said the engine sounded great all around. idle is good, etc. The issue - for a 50hp 2 stroke - from what I can find on the internet, they appear to run top speed of 25-30mph. By my fish finder, @ 6000 rpm's, I top @ 15-18 mph. With that info, he believes the engine has a smooth operational sound and thinks the propeller may have been swapped with one not ideal or damaged. Would the prop alone boost 10mph? I'll snap a pic and post it along with run the serial # and see if it's designed for this motor. How do propellers work related to pitch, 3 or 4 blade, etc. What is ideal for a 17' Edit added: Actually, the propeller is visible in the first post. looks pretty clean as in, no damage... though the size / pitch?