Hi guys, got a built 2.33 motor with gt 30/40 turbo running about 30 psi of boost. Had PFR7 grade 7 plugs and the car was misfiring like a **** in every gear at high revs.

Installed NGK BR8EIX grade 8 iridium plugs and it fixed the problem for 3 month or so, but now it started to misfire under heavy acceleration in 3rd gear and on cold days. When it's relatively warm outside it seems fine.

Now i was recommended to regap the plugs to 0.6mm from 0.7 - but now i've read that its not good to regap iridium plugs as they are too tender.

So a quick question if there's another plug i can use in that motor with a smaller gap on the same grade. Or should i try and regap ? Thanks.