Almost thought the deal was to good to be true, but, took a chance. Surfing EBAY last week and found an offer for sale of Iridium Spark Plugs, proper size and ID number (according to NGK site) for the CB550K models. I have read that they average $8-$12 each. Ebay auction was for 8 new plugs for $15 plus $5 S/H ( $1.88 each before shipping). I ended up being the only bidder.
They arrived today, two brand new factory sealed 4-packs. First impression - That center electrode is definately small at 0.6mm. Can't wait to get them installed and see if they are worth the hype. Figured I saved over $50 buying thru EBAY.