For the exhaust manifolds I used a product called Slip Plate - Graphite Lubricant. Came highly recommended from a pro mopar restorer. Just clean, wirebrush the manifolds, then spray this stuff on. It still looks perfect like the day it was applied. Much better than the Eastwood stuff I used on the RR.
Do you mean Eastwood's Exo Armor? It say's it's
"Tested to 2000F degree for temperature resistance" It can leave a shinier appearance when laid on heavy. I'm curious how it holds up on exhaust manifolds