What kind of sparkplugs are you using?

What sparkplugs do you use in your car? I'm currently running NGK TR55's and have been pleased with them. When I do my header install, I want to switch plugs [even though the NGK's have about 2k on them at the moment]. I might upgrade to the NGK Iridiums, or just stick with the TR55's.

So what type of plugs are you running and how do you like them? And should I stick with the TR55 or upgrade to Iridiums?

I'm using the NGK TR-55s and have no complaints with them. Also, you can't beat the fact that they run around two bucks a plug. The Iridiums are more expensive, but will last longer. Other then that, you won't see any gains.