The yellow stuff is the same thing as Tygon but just another brand, they both harden pretty fast. The stuff I mentioned is a dark black and a lot better, just hard to find unless you want to order a spool of the stuff. If I ever get over to the hobby shop and they have it in stock I will get the name and manufacture and post it.
OP, I found out about the Tygon and heat the hard way, I had it on the pressure line to my muffler, that lasted one fast flight before I had to land. Lesson learned!!