Rolf is spot on with his advice. I would suggest that the spreader angle in increased to allow you to play with pre-bend settings without making the mast over stiff 'sideways'. You might be suprised at how much extra pre-bend you actually need. If afterwards you find that you do have to have to stiffen it up sideways (auto depowers too much in the stonger stuff) you can then adjust the balance between spreader angle and diamond tension accordingly.

Cheshirecatman