I just wrapped mine. The ThermoTec 2" header wrap is what I used. It's about $35 a roll from Summit. You will need the metal strap and clips as well. The stuff works. Yeah, it can cause damage later (much later), but so can an unwrapped pipe. Hell, I had protective sleeves on my MSD wires and still burnt through one of them. I can build a new down pipe in five years IF anything ever happens.
1990 LX Coupe 5.0 5 speed w/ 2000 Exploder GT-40 engine, P heads, mystery cam (F cam per previous owner) 3.73, and not much else. In the parts pile - UPR tubular K member, CC plates. Future plans - Megasquirt & On3 turbo system.