Hi Mart
Nice looking hull (as we said when "Phantom" first put them on here, sooo long ago)
Nice shade of
red ORANGE
I like the new top and there is lots of area to open up for a centre exhaust (unless you're going under deck, then it won't matter).
The spray rails on the bottom look interesting. You will have to set it up to corner 'nose up', as the two front rails finish well forward and there are only the two wide rails at the rear, so set the CB well back otherwise, when you go into a corner, the front will 'grip' and the back will 'slide', giving you a spin! You will probably need a turn fin(s) on it.
As for venting - the principle is sound but remember these boats don't go as fast as the real thing - and air doesn't scale. So to get sufficient air to the step will require some sort of 'ram scoop' on the top. I would just rely on the fact that SOME air will be drawn under the hull from the sides and leave it at that!
There are many more ways (most easier) to get more speed. The step should give an increase on it's own, so I wouldn't be tempted to start 'air injection' at this stage. You can always try it when you've got the most out of it and are looking for the 'extra half mph'.
Good luck and keep us posted.
Danny