Foil mounting position?

I got a new pair of foils last week to replace my old thrusters. I had them mounted at the local shop. My old thrusters were mounted at the traditional mount spot. The foil's bindings are mounted further foward. I am unsure where salomons suggested mounting position is, and if my skis are on the suggested mark. I got to ski on them, and they seemed more difficult, and weird to carve with, and no better in the park since I am used to the binding position on my old skis. They arn't true center, I checked they are probably 3 or more cm's back. I ski 50% all mt, and 50% park and I dont know if they should have been mounted further back for me. I can probably get some pics later if that would help.