Motorcycle Repair: FXD front end mods, triple trees, stanchions

Question
I own a 02 fxd and want to tweak the front end, by putting wide triple trees on.  I heard that for every degree of increased rake, you must extend the fork stanchions by 1 and a half inches. Is this correct?

Answer
its roughly correct. What you want to do is some measuring. Add the degrees you want with a protractor and run a string at that angle. Hole the string up from the floor to where the axle measurement would be and then measure the string and that will tell you how much more you need to extend the forks
Good luck and happy riding
Mike