Back country 189 pro guide help

[drewzx3]

Trying to get a little more speed out of my boat. It has a 01 150 vmax on it. Someone changed the lower unit to a 1
85 ratio when swapping lower units instead of a 2.0 it has a tempest plus 21p on it right now and will only turn 4900 rpm trimmed out and 50mph. I've tried a Yamaha 19m and could turn it 5300 but lost a mph. Also have tried a quicksilver torrent 21 and Yamaha 21m both would turn 5200rpm but no speed gain. The boat also has a 6" jackplate. Is the lower unit gear ratio hurting me? Everyone I have seen with these boats claim mid 50s to low 60s mph.

[XstreamVking]

The back country boats have a lot of variation in the hulls. Some will lift the nose and fly, most are hard to get the bow to lift. Check the bottom for a hook and see what you have. Straight edge or a string from back to front and see if you have a gap.