jdl,
These are only my personal thoughts. It's what works for me.
Earlier in the thread I mentioned sail balance. You got some respectful speed out of your Ty. If you were a dedicated racer, you probably would have a greater variety of foresails. You mentioned a 105% for a windy day test and a 155% for an earlier test with lighter wind speed. Something in between might be of benefit.
I think that if you had a little more canvas set up front you wouldn't have the weather helm. With the perfect sail balance, you might find that you had no helm to speak of, weather or lee. Every time you sail with your tiller not in line with the hull is like sailing while dragging your brakes.
Maybe, try sailing on various points with your tiller temporarily lashed dead center. Note where the hull tries to to go, upwind or downwind. With little or no helm, you should pick up a bit more speed.
Otherwise, just go sailing with what you have in the sail locker and enjoy your gem. Just don't race.
Good luck,
O J