The tabs on high-speed boats like your brother's are mounted horizontally to reduce drag...they still have the same effect on the hull's performance.
The following was a response from a reader on Reel Boating Forum..."Mr Demeanor"...he explained it pretty well I thought...
Just an idea for others with the same issue. You dont have to run the tab parallel with the angle of the hull at the tramson. You can run them more "level" and use a slightly longer tab. Many high performance boats have the tabs mounted completely horizontal. This prevents them from acting like "brakes". If you think about it, tabs mounted in the traditional position like those above are moving in different directions as they go down (slightly port and starboard of the boat). By mounting them horizotal, they both move in the same direction which reduces drag and increases efficiency. It also decreases the tabs tendancy to be make an abrupt change in running attitude as they are depolyed. The outer edge ends up contacting the water first and then more and more of the tab as they are lowered. This would have moved your top hinge outward quite a bit.
Take a look at the transom shot of this Fountain for example:
http://www.yachtauctions.com/detail.asp?stockNo=19923
Notice he mentions and look at your brother's boat; longer tabs as they have to "reach" further when mounted horizontally...mine were a lock for traditional mounting as they extend 8" out and would not get enough surface water contact mounted horizontally...
BTW...beautiful Go-Fast yer bro has there...but given a choice, I'd rather have "Bump-Kens"...