1988 V20 with 225 Honda

[jackman1939]

Finally got my new T-top made and installed on my boat. Took it out a few times. Boat used to go 44mph (with the old T-top), now it only goes 40mph. Gets about 2.5 miles per gallon. Seems to me that it should go faster than that. I have to keep the trim very low - when I try to raise it, the boat porpoises a lot. I installed one of those anti porpoise things on the motor, but that didn't really help.
HELP !