If you spend any time searching on brake lines, you'll read lots of opinions about how our cars come stock with braided metal lines and you're an idiot for wasting your $$ on aftermarket braided lines (or something akin to that...) but you won't find any facts to back up those opinions.
I recently did the A8/TT upgrade (with Tyrol Sport bushings) and replaced my lines with new braided lines from ECS. I came across one of the old lines today and decided to do my own version of Mythbusters...
Here's the line I used already cut in half:
Here's the closeup of the cross-section piece I cut out of the center:
Doesn't look much like metal, doesn't it?
After peeling away the outer rubber layer, we have the first layer of cloth:
And with a little careful slicing and separating, here's the second layer of cloth:
A little more cutting and we now expose the inner rubber brake hose:
And finally, just for effect, here's the cross section of all 3 pieces:
The brake line is off of my 2001 B5 GLX V6/5M and has ~185,000 on it.
I used a razor blade (box cutter type) and a small common screwdriver to do all cuts and separations. If it was any sort of braided metal, I'd have never been able to slice it like that!
Hopefully this helps someone to make an informed decision about replacing their brake lines in the future!