Hello, I have a single turbo 1993 RX-7 that always seems to have the front trailing plug get black looking. (poor ignition)

I have had multiple plugs in this position, and no matter what plug is in there, it turns black. In fact, if I take the two trailing plugs and swap them, the black one turns brown (normal color) and the one that was formerly in the T2 position now becomes black. I have also tried several NEW plugs and they all end up black in that spot.

This happens with BUR9EQP (stock plugs) as well as BR10EIX plugs.

I have an HKS Twinpower ignition and the other plugs all look the "right" color. The car drives fine and pulls hard all the way to 8000. I also have some Magnecor upgraded wires put on by the previous owner. I don't know how old they are but the car only has about 50K on it, so they can't be THAT old.

I've replaced the plugs several times as mentioned above, and I also swapped out the T1 coil for another used T1 coil off another car. The plug in T1 still turns black. At this point I think it pretty much has got to be either the wire or the stock ignitor unit. I tested the stock harness from the point where the HKS Twinpower hooks in, and all the leads are good. The grounds found on that small bit of harness are also good and clean and tight.

Anyone ever have the ignitor die out on JUST one position? I don't know much about how the ignitor works... maybe it's either "all good" or "all bad" and doesn't differentiate between L1, L2, T1, T2? I'm going to order a new set of wires I think also just to be safe.

I am hesitant to disconnect the twinpower because I run 15 PSI and a single turbo and I don't want to risk something wacky happening

Ideas?

Thanks!
Brian