Hmm... 1.8mm-2mm would be good for a 8.6:1 set up. I'm not sure what does the mechanic meant by 1 more time skimming... Cause I don't know how much material is skimmed from ur engine head. But it won't be anything more than 1mm. If 1mm, the cylinder head cannot pakai liao...
Have i missed anything in my previous post..? I mean, he rechipped his ECU to 9krpm, but the e-manage only till 8krpm.
But I wonder if he tell the shop that he's gonna boost that high when he does the rechip. Cuz, if the shop knows owner's boosting so 7 high, he would have map for 9-10 AFR and retart the timing at top end within the ECU itself...
Anyway... that's just to let u know that any piston fails regardless of boost... it's the tunning... And BTW, whatever ECU u gonna use... There's no way of getting rid of detonation... U'll just reduce the risk. That's because u have full control over all the mapping within the ECU. Detonation is part of the thermal property of the fuel... Not the ECU.