Just a general interest question.

What are iridum spark plugs, how do they differ from normal ones, and what are the benefits of fitting them?

TIA.

Cheers, Trev.

Good questions. Here are some answers:

http://www.sparkplugs.co.uk/pages/technical/iridium_spark_plugs.htm

Thank you, very informative.

^ +1 DGW

Had NGK Iridiums (last longer than Denso as tip is IIRC 0.6mm,against 0.4mm on the Denso) on my old Vectra 2.5 GSi for most of the 8 years I had it (sure I read it recently that they were the OE plug on the Vectra 2.8VXR's). Fantastic plugs and never missed a beat. Didn't buy them for any 'power' gain, no plug will give you that, more for the fact that they last longer than 'normal' plugs and produce a spark at much lower voltage.Thereby putting less strain on the ignition system.