FreakTune. I was stock minus HPFP and an intake. Was tuned to 18 PSI. I agree spark plugs shouldn't crack like that. I told him I was running stock plugs
Sorry to revive an old thread but I thought I'd share my experience.
My 2012 Speed 3 just did something very similar. About a year ago my engine had 170 PSI across all 4 cylinders. A month ago I changed my spark plugs with NGKs. Car ran great. 2,000 miles later I went to check compression...