Believe or not the headers start from 620 not coated going up to 850 coated built to your specs. As long as we are seeing gains then we will keep making them with adjustments. There is some controversy about the choke on this version. Well 2.0 with nitrous is why I decided to try this version along with the fact that I'm building another motor on the side. He does plan on building a more stocker version with the 2.25 choke.