4inch to 8 inch jack plate is it the right decision?

I have a 1999 tr-19 with a merc 175 efi with a 24 tempest on it right now it has a 4 inch jack plate and will run 61 fully load two people and full on gas and running around 5100 rpm and i know i have more motor left and i have played with the jack plate some but cant gain any more rpms. i can currently get an 8 inch manual jack plate for free right now but i was wondering if it would be to much for my boat or if it will be good for it? let me know what you think thanks!!!

I'd go for it.Should get a little more speed and control out of the 8" And it's free!!!

+1

+2 hydraulic would be nicer but who's going to argue with a free one.