Paint on headers, for a couple of minutes, lol. Usually does better then a couple of minutes if you used the hi temp stuff. If plasti cost, probably not. Could also be running lean at idle And higher temp for that reason. High temp powder paint works for a little while, but eventually fails. I have it on my headers and it started to fail after year two.
I agree, and yep it was Rustoleum high temp. If I have time today, I'm going to throw my timing light on it to see if it's too retarded.
