http://cgi.ebay.co.uk/DENSO-IRIDIUM-Spa ... 286.c0.m14
comparison with standard plugs but i have read with a decent plug there are no performance gains with iridium but i recently fitted them to my bike and it did feel better
i wouldnt clay if it picks off the spots of paint it will scratch
i would use white spirit on a rag and allow it to sit on the paint rather than rubbing it
wash well and polish