Just bught a IMCO adjustable water pickup & would like to know where on the transom is best to mount it. Also how far from the bottom is it supposed to be.

Single or twins????

Mount it so the trailing edge is about 1/8" below the hull. You don't want it disturbing the water that is in front of the prop if at all possible.

Here is a pic of mine for referance

It's a single, thanks for the pic. So 1/8" below bottom of boat?

Your pick up is adjustable right? If I were you, I would mount the pickup so that the highest piont is flush with the bottom of the hull. Then you can alwyas adjust down if you have to.