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Probably worth replacing your spark plugs, but I doubt that they're the cause here, especially only running Stage 1 -- not too aggressive. My money's on the ignition coils. From my E46 M3 days, I was under the impression that coils either worked or they didn't, and you'd simply replace them as they failed. With these turbo motors with higher-than-stock boost levels, I'm getting the impression that might not be the case, and that while spark plugs are the first culprit, coils should be your second. With so much mileage (presumably on 86k-mile coils?) and you probably needing to do plugs anyway, I'd personally suggesting replacing all 6 spark plugs and coils and see if that fixes the issue. If not...may be an injector issue and someone else on here would have to speak to that.
For what it's worth, I've had misfires on a custom MHD tune that was attributed to spark plug gap not being tight enough (I had .026, while recommended is .018 for MHD from the looks of it), and despite trying OEM Bosch plugs and NGKs both gapped to .018, I'm still having "hesitation" issues. Only 41k miles, too. So I'd suggest at the very least replacing the coils on the cylinders that have misfires. I suspect that people may start replacing coils and not just plugs to sort out misfires going forward.
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