[Alan Roehrich]

Back to back testing within 24 hours on one set of headers, under very similar conditions, showed an approximate 2% gain in HP on 500HP 406 small block, with tuning to compensate for the changes the coating created. The headers were coated with ceramic/aluminum coating inside and out. The coating raised the EGT's significantly, and required a jet change to richen the A/FR. The engine was tuned for peak HP with the uncoated headers, the headers were removed, coated, and re-installed the next day. The engine required a jet change or two (richer) to bring the EGT's back in line, and the result was about 2% more HP.

If you have your engine tuned to be as lean as possible in order to make maximum HP, with uncoated headers, when you coat the headers you'll find the EGT will go up, often by a significant margin, as much as 200 degrees or more. You may lose HP, or not gain any power, and you may discolor the coating, no matter whose coating it is. We have seen it necessary to go up 2 to 4 jet sizes to get the EGT back to where it was before the coating was applied.

If you leave mild steel headers uncoated on the inside, the unprotected side of the tubing will rust, header life will be reduced, and you may lose HP.