i'd say as you've got the whole '90 spec kit you might as well keep the big bumpers, unless you fancy changing the arches, sills etc. also depends on the look your going for. if you want old school, euro style with massive drop and cool wheels go small bumpers. if you want to keep it at a reasonable ride height of 40mm drop and not so rare/old school rimns i'd say leave the big bumpers on.