I have a 16' Alumacraft and I put these on:
http://www.nauticusinc.com/smart_tabsSX.htm
I didn't want to deal with the wires and hydraulics and expense of the manual ones.
They made all the difference in the world. I'm on plane at 15mph and don't porpoise anymore unless I trim too high. And the boat steers like my Mustang. Flat in the turns. Watch the videos. They do exactly what they say they do.