What is this stuff??

I finally got around to stripping the aluminum covers off my old 308 headers. Basically, the metal was so soft I was able to peal it open like a tin can. But I found some stuff inside that looked to me like fiberglass -- a combination of long shiny threads and matting that looked like cotton batting. I approached it from the point of view of it possibly being asbestos, so I used a respirator, goggles, gloves, coveralls; wetted the stuff down as I went to keep dust to a minimum.

So, was it asbestos? Fiberglass? Rock wool? Some other unknown substance?

 

Yes, that looks like the stuff I found in mine -- the fuzzy white stuff toward the top. BTW, my pipes are in perfect condition. I just have to have the bungs welded up and clean up some of the metal and then I'm going to send them off to Jet Hot for coating. I'm thinking black, but since I'll actually be able to see the rear pipes, maybe silver would look good.