Ok, I have been messing with my boat trying to get better #'s out of it.

With twin OX66 250's , spinning 3-blade 15-1/4 x 19 pitch props, with a radar arch and a full tank of fuel, trimmed way out....

I'm only seeing 55mph on GPS at 5200-5300 rpm's?

Shouldn't I be seeing more like 65mph?

Motors have 100hrs on them, great compression, tuned up, but I don't understand.

People talk about 62-68 on these boats with twin 250's.

Spin the props in, move the motors to the highest hole and see what you have. Ours ran 62-64 any day of the week with the ox66 250's. Those motors should always spin over 5500 to make their full power.

Tried mine spinning in, got 1-2 mph, but dock manners were SO bad I switched them back to spinning out.

Is the stand off box free of water? Is the compartments next to fuel tank empty? Both like to hold lots of water cause drain holes clog.

Otherwise, I dont know. Motors getting to 100% output?
Mine has Evinrude 225's and will run 60 with bravo 22's (4 blade) and 63 with mirage 23's (3 blade) at around 6000 RPM. (all GPS speeds) The bravo's REALLY make the boat ride SO much better and eat waves, it is worth the slower speed.

Docking isn't bad as long as you trim the motors a little above neutral.

So I should be turning 6000 rpm's...

Where can I drain my standoff box, mine is a Stainless Marine.

I haven't even looked at what settings the motors are on the bracket, better check...

Thanks guys!

Big plastic plug underneath.

Aim for the motors to be at 5500 with full fuel and full load of people. If the bracket doesnt have a drain built into it, just take the covers off and pump it out through the top