18ft concord cavitating

[blkz28]

i have a 1979 evinrude 150 with a 14.5x19 stainless prop as soon as i start to trim up maybe 2 inches the motor will start to rev higher and the speed slows down any help would be great the motor is as low as it will go on transom but cav plate is about 1.5 inch above bottom of boat right now it tops out at 50.2 mph gps would a extension help out it gets on plane very fast even with 5 people

[jlfastride]

as i understand an extension plate will help , but i am a virgin to boating and hp mods im sure someone else can help you alot more than i. don't take my word for it . just what i beleive i have learned by reading other links and posts. gl jl