We socked it to the stripers trolling at 6 - 8 mph out of Oregon Inlet this time last year using diving plugs. I couldn't believe how fast those 15 - 25 lb fish dart to grab those plugs! I always thought striper should be trolled slowly....until last year ;D
But, to answer your question from one particular angle, I've got a 70hp outboard with a trolling plate attached to the lower unit. Its a trolling plate with springs on it so you don't have to raise or lower it. For anyone who doesn't know, a trolling plate blocks the thrust of the prop to slow down your speed.
The one I bought was a "Hussle Trolling Plate". I love it for flounder fishing in small creeks. It took my 17fter down from 4mph to 1 - 1.5mp. Its great for docking too! The thrust of the prop pushes it up when you gas it up. Here's a pic:
My only complaint is that it did not come with stainless hardware so its pretty rusty looking now! Just the springs and bolts of course!
Blue