I sent my set of mechanical carbs to Pro-max and had them do their stuff to them including a rebuild. The 493 inch hydraulic cammed motor they are on dynoed out at 681 hp/682 ft.lbs of torque at 5500rpm. I assume the vaccum advance models would produce the same output. The differnce is in the drivability. I like the control I get with them. They do require some thought to use effectively, but they teach you how to drive them by the seat of your pants. Too much too soon, and you feel it. Crisp is a good word to describe the way they feel. A set of well set-up vacumn carbs don't require much skill. You just mash the pedal and they do the rest. Mushy sounds about right to describe the difference.

I ran a set of the mechanicals back in the late '70's early 80's and absolutely loved them. One day the outboards stuck open on the freeway, which gave me a feeling that I'll never forget. I had to stomp on the pedal again to get them to release. What a ride!