Did a few quick materials tests on the upper radiator hose, since I didn't plan on using that one.
Specific gravity of a chunk of the material is equal to that of the silicone couplers which I am using in my IC piping, both the ones that came from Driftmotion and the ones that came from Mopac. Not exactly mass spectroscopy, but this is as good a comparison between the materials as I could make.
Boiled the hose in a pressure tube with the relief valve at 75 PSI. This should give the water a boiling point of about 160 deg C. (Should have taken video of the pressure release.) Immediately put pressure on the hose to deform it (Hot water under pressure from the air compressor at 30 PSI), which it successfully resisted, so it's good for immersed temperatures of at least that much, which is hotter than the coolant should ever be. Poked and prodded it with progressively hotter tools until it did deform, but the pliers were pretty much glowing red at this point, so unless they need to survive direct contact with the exhaust manifold or turbo hot-side, I think that they'll be okay.
For what it's worth, I ordered the kit in eBay mafia blue. I figured what the heck. All of the existing silicone couplers in my IC piping are blue, and the silicone vacuum hose kit that I've got is blue...