I incidentally have been using Pulstar plugs, http://www.pulstarplug.com/index.html in my 06 Z06 and have noticed a bit better MPG, always over 20, and the kick was noticeable the day they were installed.
Yeah, I've read about them, but at $200 for a set, I wasn't inclined to be the first on my block to try them. Interesting to hear you had noticeably good results from using them......