I just wrapped the starter with a heat blanket. I also removed all insulation off the firewall and the a/c box and painted the firewall and undercarriage black. The insulation on the firewall was hanging down onto the exhaust and the a/c was well, just ugly. I pulled the interior and added dynamat type sound proofing and heat shield material to the firewall and floor and that took away all the added noise and heat created from the headers. The a/c is still as ice cold as ever with the fugly insulation removed for four years now.
My headers still look great after years of use but it rarely ever sees moisture.
If your only interested in heat and looks, ceramic coating them in and out is your best bet. I just didn’t have the finances at the time and wanted to focus more on cleaning up the engine bay and undercarriage and sound proofing.