Dave.
Your are looking at tacking angle as if that is the metric. You best metric is VMG, Velocity Made Good. This is not a static angle. It is a performance metric that changes with each leg of the race.
If I say 38º off True and you go out on the course searching for 38º you may find that your boat is doing better at 45º on a given day, wind speed, gusts, puffs, headers etc all taken into account. You may find that the right side of the course is better than the left when you consider the lees of buildings, the currents, the chop.
With your sails and the way you are rigged, you need to go out and practice wit your boat finding the best set up you can accomplish. I recognize that all boats are not set up the same way even if they are the same brand and are using the same sails.
Work the problem over a set course. Test and record the settings of your sail trim. Record your VMG with that set up. Then go back and do it again. Did you have the boat pinching, were you rounding up because you were healing at 25º or 35. Were you constantly causing the rudder to drag trying to point as high as your competition only to slow down while sailing out of balance? Were you maintaining speed through the lulls and taking advantage of the puffs?
I would encourage you to read "Fast Handling Technique" by Frank Bethwaite