Hi guys.
So after having some NGK Iridium IX plugs installed by a shop and getting some misfiring and high KR, I ended up putting the old plugs back in myself (they looked pretty good) and doing the coil stretch mod as per How To: Ignition coil spring stretch mod - Mazdaspeed Forums
While the misfiring is gone, I'm still seeing a lot of mild KR (under 2) which I never used to get and the occasional KR in the 4's when punching it.
I'm wondering if anyone had an idea of what else could have been disturbed when they installed the plugs? Tune is by Lex at Stratified and has been knock free until then.
Cheers!