[89IROC&RS]

good ol AC Delco plugs are what i run in my 89 IROC. Spark plug is a spark plug is a spark plug. Just make sure they are proporly gapped, and they will do their job. You could also use bosch platnum +4's, but while i feel the theory behind the design is solid, ive never seen any back to back testing to proove they do the job any better than regular spark plugs. So for a price to effectiveness suggestion, i say run the AC Delco plugs.