Tim / Whaler,
The JC Whitney stuff is the same as underlayment with the added two layers of aluminum.
This product -
http://www.jcwhitney.com/productnoit...D=5311&BQ=jcw2
I've got to admit I get blank stares when I say "JC Whitney" and "Cobra" in the same sentence. It doesn't have the macho punch that "Summit Racing" or even "NAPA" has. It's right up there with "Woolworth" or "Dollar General" as far as people's perception.
Truth be told, I have ordered quite few things from JC Whitney that have been satisfactory. Taylor wire loom, insulation, wire ties, stainless steel clamps/fasteners etc.
Other similar products like those mentioned by others on this thread
keyword "insulation" on JC Whitney's web site
http://www.jcwhitney.com/catsubpic.j...questid=155365