Artificial-I - just for something dumb try a 77T odonnel plug - only brand plug I'll use.
I am running the old old version D5 (not the R version), this engine is over 1.5 years old and raced at two clubs so shes done a bit of work and abuse. My friend with a OZ TZ well, I can't say it raised my eyebrows. IMO the old D5 and the new TZ where comparable though I assume this is due to tune and or gearing. Maybe something was wrong with his engine because the piston (on the OS) did fly apart later that day!
Maybe engine was not fully broken in?
I am hoping the D5 will die soon and I can move on to the STS R series of engines
For the price IMO you cant beat'em, why else would I have 4 STS engines and nothing else, oh, and Dino's support ofcourse.. Hi Dino !!!.
Just gear the car up a little more and off ya go.