wideguy

Covered in carbon isn't the normal appearance of a plug from a fuel injected engine... Except I know nothing about your restricted hp engines. Perhaps they normally run rich? Our EPA wouldn't allow that.
Putting hotter plugs in a rich running engine is a cheesy way to stop the over rich mixture from fouling the plugs and stopping the engine.
Then again, is it wet carbon, or dry and fluffy? Wet would be oil fouling, also cheesily fixed with hotter plugs.