I have been running a 27 txp ot4 and it runs 79.3 mph @ 6100 at 1.5" below pad. I have a 28p raker that I am running 1.5 to 3.5" below pad. It runs 12 psi when I run it high, and 25 psi when running low. I can run 78.7 @ 5900 with the raker. I have brought it up and it just picks up rpm and loses speed. Both props have been worked over by Mark. Everyone tells me to raise the motor, I have and I lose speed and just pick up rpm? I posted this awhile back and am looking for suggestions. Maybe a 29p ot3 @ 1.5" below pad.