If the headers are made of normal steel or metal that can rust I would agree about not wrapping,HMF headers and pipes are stainless and dont rust! Its up to you, these headers are almost always larger in diameter,therefore closer to the plastic,if you want to take a chance,you wont know it till its too late.HMF says if you have melting problems then its not installed correct, they've engineered enough clearance in the design, I just didnt want to take a chance, Ask Pipefighter if he wrapped his.