I have managed to find 12 IXU24 Denso plugs for the 2001-2008 bikes. these are the best plugs you can fit for the bikes as long as all else is well.
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... _500wt_715
apparently, the Denso factory is making high spec plugs like these for OEM cars and all...