Iwould call the guys at eastwood and por 15 and just ask them if their stuff really works .It might be that you gotta do some good prep work such as taking all the old coating off ( what ever is left) I too have had bad results with header paint . The rattle can stuff is crappy . The headers I bought for my 40 coupe were ceramic coated and seem to hold up well. There is
another company that sells high temp paint but i forget their name , when my brain finally gets in gear this morn I will
try to remember thier name and post it .