Ciao Frederik - try to move the foil fwd almost to the front, go for two or three runs to see how it feels. If it is too nervous/you have too much lift/front foot pressure, then keep moving the foil back step by step until you feel comfortable. Mast track in the middle. Usually if you put the foil in the centre of the boxes, it will feel pretty balanced. If you are a better foiler and want more speed, then set it up backwards closer to the Tuttle option position? Bigger sail should not be needed, you can just pump a bit more at the start. Shims you can play with, but sounds to me like you have the foil too far back.