I have a sail of the same sailmaker and I'm sailing with an almost straight mast when cat rigged. If I don't do that then I get what you have. Other things to tune are traveller and the foot of the mainsail. Both seem to aggrevate this behaviour when set wrong.
Ironically, on Friday I set my mast rake fairly straight ... went out for a sail and had neutral (to leeward) weather helm. When I hit the beach I raked back (primarily to de-power the boat as I thought the winds were going to be too high for me as a uni). I guess I should have left the settings as the drag on the rudders certainly de-powered me <img src="http://www.catsailor.com/forums/images/graemlins/frown.gif" alt="" /> to the point of being frustrating!
Thanks for the advice....a picture certainly is worth 1k words.
