A buddy has the same set-up, except that his water dumps out the transom and falls 6-7 inches right onto the top cap. The key is the transom mounted pickups for the engines cooling water.
The drive water pickup water hose on the inside of the transom is routed straight up and right back out the transom. At speed water is forced up the inside of the drive and right back out as drive shower water. My buddies dumps the water, this set-up carries the water through the hose to the top cap.

My Cigarette has water that dumps on top of the drives. It is split off at the exhaust, so it is HOT. I use Halo Max drive showers and they are great. The side walls on the drives are what you need to cool. They are thinner. I have a 1994 38 foot Cigarette TOP GUN that weighs over 13,000lbs when fully loaded. I have twin supercharged 600hp engines on the old style bravo 1 drives with the 1 inch prop shaft. I also have 5 blade Maximus props. I have not had any bravo 1 problems since I bought the boat in 2004. Knock on wood and I think it is because the Halo Max drive shower's have kept the temp down. Also, I don't go more than about 6 miles before I set her back in the water. The freshwater lake is small.

look closely,,,,,there is a crank shaft raw water pump that look like it feeds the showers along with the factory bravo raw pump in its usual place