Had to tear down the motor so I decided to do a port and polish as well as polish the valves and the inside of the heads. While I was doing this, I couldn't figure out if the black stuff that was coming off was just carbon or a factory ceramic coat. I had the FSM and it did say to de-carbon the head and said nothing about being careful not to damage any coating. Don't know if it will really make a difference but I'm really wondering. I'll be having the pistons coated for nitrous but don't know if I should bother with the heads. Anyone know anything about this?