Oh - those are flaps and not speed breaks. I see now you have a REALLY old kit - it's the fixed gear version.

Mine weighs 14 lbs ready to go. That's with glassed surfaces. I have 2 and one has flaps fitted. I will post some pics of it.

I would be hesitant to change the airfoil though, this one is probably the best, most well behaved skyhawks around. Too bad they are not made anymore. I never really had the dreaded skyhawk tuck at slower speeds. Most of the other models out there will tuck pretty bad in a turn at slower speeds, but they all do it to some extent.