one of my friends is getting a vis mugen kit and heard they fit like shit too. dont know if that applies for all of them, i hear vis's cf hoods fit well.
skirts and rears are no big deal really, it's easy to get those fitted or to drill some new holes. front bumpers though are another thing. i havent seen many mugen replica front ends that fit perfectly, all have that little gap from the fender or don't line up perfectly, and to get it fitted i don't know what a body shop does, mold something or cut, yea. a lot of ppl get original mugen front ends and knockoff skirts and rears. too much imo.