They Are About More Than Just Looking Good. Hedman's HTC Ceramic-Metallic Coating looks great, but there is more to this coating than its good looks. Without it, uncoated hedders don't stand a chance against the intense temperatures of your vehicle's engine compartment, or the corrosive elements found on the road every day. Bonded to the hedder with a strength factor exceeding 10,000 PSI, Hedman's HTC coating will not flake, chip or peel like Chrome, or cheaper products. HTC insulates the hedder tubes, keeping temperatures in the tubes higher for a faster exhaust flow, and reduced under hood temperatures. Hedman started the coated hedder trend in the 70's, and has perfected the process. Hedman guarantees these hedders against external rust-through for a full five years. Painted Hedder 1975-1986 Ford Mini Motorhomes (Class "C" Converted Vans) 460 (7.5L)