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Plugs should be gapped to about .026. If they weren’t, you may need to pull them if they’re brand new and just recap them with a proper gapping tool. That said, with 55k miles, depending on the type of fuel you’ve pushed through the system, it might be time to change out your fuel filter. On a performance car, especially if you drive it a lot and aggressively, fuel filters should be changed even if the manufacturer doesn’t call for it. For your old plugs you pulled out, do you have pics of what they looked like? Sometimes the condition of them will tell you what might be going on. Also keep in mind that some knock can be expected from time to time, as long as it’s not extreme and as long as the timing correction associated with it isn’t by several degrees before it stops, it’s usually acceptable, especially on a factory calibration. This platform doesn’t have issues with blown intercooler cores leaking coolant into the intake tract of the engine, so something like that causing misfires is probably not your issue and if power delivery is smooth, it’s not that.
In terms of custom tunes, remote shit based on logs aren’t the best way to get a custom tune, I don’t care how long your supposed tuners has done it for. If there was knock in later revisions, then timing needed to be dialed back to give you more headroom. That said, it that tune was the problem, you would have seen an immediate improvement when running your based map and you said you didn’t. So, you’re either at fuel quality, possible dirty fuel system or something else. For now, go with either the Stage 1 OTS or the CSL map and check the gap on your plugs per what I said above. Then run a bottle of Gumout Regane (the skinny bottle) fuel system cleaner through the engine with a good tank of 93 from a reputable station. If you continue to have some issues, your next thing to swap would be your fuel filter, even from a good preventative maintenance standpoint. If you still have your old plugs, take some pics and post them if you want so we can see what they look like or even post pics of the one you have in there now that you need to take out and regap anyway.
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