Your stockers are 50mm offset.
Alignment (toe in/out, camber etc) shouldn't change as long as you are using similar sized rims (i.e. 15") and tires - but your scrub radius will change a bit when using the +43mm offset Mugens (14mm wider track).
Alignment changes more when you raise/lower the car - vs widening track width.
A similar post a while back did not get much input:
[Modified by Big Phat R, 3:42 PM 1/28/2003]