how many rpms would 20hp give ya?

[jimmyz32]

I bought a 25" mid section for my fishing boat and left the 150 tuner in it " i was told by a local mach. that the tuner was the same on the 150 and 200hp when it comes to the 25" mid." so i put my 200 efi powerhead on it and it just seems it should get more rpms. So i called mercury raceing tech line and a mercury tech said that i could have lost 20hp. because the tuner for the 200hp motor is 7 1/2" even on the 25" mid. And the 150 tuner is 13" long. Thats why i am asking this question. I am only turning 5300 rpms and 48 mph if i could get 500 rpms more i would be happy.

[illMATTic]

were you running a 20" mid before hand? what rpm's were you turning before the swap? same gear ratio in the lower?

[jimmyz32]

my 200 efi powerhead came off a 20" mid and i left the adaptor plate and tuner in itwhen i traded it. i have never ran a motor on this boat before.

[jimmyz32]

oh yah the gear ratio is the same 1.78