i don't think it should ... ive got one in mine and have taken it off to clean it up ... looks like they only cut throught the roof skin nothing to weaken the car ...
and plus since your gonna do a f20c or 20v conversion with oboviusly more power then those motors produce (f20c or 20v) the logic thing to do is to strengthen the chasis... either seam weld or a proper cage .