i'm currently toying with the idea of using XB4 rear arms on my B4.1 (or what is left of it), the problem is: they have 2 mounting locations for the outer hinge pins and the car will be either much wider or much narrower than stock. (approx. 3-5mm per side) What effect will a change of the rear track width have?

my options would be:
B4.1 rm3: much wider/narrower
C4.1 mm4: a bit narrower
B4.1 mm3: much wider/narrower