I didn't even pay attention to the porcelain just the tips and straps, I'll look again for carbon tracking. I guess I'll get a new plug and boot ready.I don't see anything overly alarming there. The porcelain on one plug appears to be cracked and the boot appears to have signs of arcing down in the plug well.
This said, though the carbon on those pistons isn't scary (I've seen way worse), it's a definite sign of being too rich. That can be anything from the tune to bad injectors.
Are you completely comfortable with your tune?