Pay attention to all components of the tuning guide. I sailed with my mast butt 3/4" too far aft for a couple of years, and I could never get the rig to set up right (way too much prebend).
Mast butt max forward, headstay class max, THEN start setting tension according to the guides.
I have North sails, and generally err on the light side of tuning ranges. We go pretty floppy in light stuff-seems to be fast.
