they were 502's with merlin heads etc as per teaugue est hp was 550.

Jonas,
Thanks for the input.

T.J.

I would see what happens with some 28" B1's

What is your prop height with the shorties?
Trim your drives so the prop shaft centerline is parallel with with the bottom of the boat.
Lay a straight edge on the bottom of the boat directly in front of the drive, extending back towards the drives.
Measure the distance from the bottom of the boat(directly in front of the drive) to the centerline of the propshaft.
What is that distance?
DS

JONAS, what was your top end on the '92?

low eighteis

Toolbox, any progress with those imco shorties? I was thinking about doing a set myself.

One of my boats was a 35 lightning and you will NOT get any speed even with extension boxes. The advatage that the shorties have is when your speed is in excess of 90 MPH. At this speed or higher you could expect to see 3-5 MPH over stock length drives. Also keep in mind that fountains have a very high x-demension already, the hulls are pretty much tweeked as much as possible at the factory.