but lets do the math:
an engine that over time achieves 45k miles:
new copper plugs every 3k = 15 sets of plugs. 15 x 8 = $120.00, plus the extra time to actually gap them and change them at every oil change.
new irridium plugs: $28 for the set, never have to re-gap them, never have to replace them.
coppers will last longer than 3000. Even on my high compression motor running fairly aggressive timing they still last me about 5000 miles before i see the AFR's start to act up. but i no longer DD the car so i'm for damn sure not about to run an expensive plug.
Shopping for plugs for my N/A build brought me here. I'm seeing two sub-part numbers for the BKR7EIX (BKR7EIX/2667, Civic R18; and BKR7EIX-11/6988, K-series, B-series VTEC, and S2000), and I can't tell the difference between them other than the -11 being pre-gapped to .044" (source). Does that mean it's not designed to handle gap adjustment, and so the 2667 is simply a more universal plug? Neither say they 'fit' the Prelude, but I just want to double check with anyone that might know: