I always use Nylon hose which is also commonly used in air brake applications. It is high pressure rated, has excellent hi-temp, oil resistance and is quite flexible. Available in a variety of sizes, I have completely rebuilt TI and TII vacuum harness cars with this stuff. It's great for turbo cars where engine heat is a major issue over the intake where temps frequently get to 200*F or more. At these higher temps the inexpensive PVC (poly) hose commonly sold at the auto parts store easily melts. The poly hose is typically not the emmissions grade hose that they also sometimes sell in a blister package or plastic bag, like 3' at a pack. That is or should be vinyl hose.
I get my stuff at: EVCO House of Hose in Salt Lake City, UT
You can get it almost anywhere they sell air brake tubing...like: Hose and Fittings, Etc | Parker hydraulics & pneumatics in CA & NV
It is also easily found on eBay...it's made by Edelmann
Summit Racing sells it but its special order
Just search eBay or Google for "PFT-4A"
The PFT part is the type of hose, there is type 'A' and type 'B'. You want type A. The reinforced type 'B' actually has a lower burst pressure....but it's still something like 1200PSI.
Parflex Tubing (PFT)– Nylon tubing designed for use in tractor, trailer and other mobile air brake, instrumentation and air accessory systems.
Meets SAE specification J844 Type A or B, D.O.T. FMVSS106, and performance requirements as specified in SAE specification J1131.
Heat and light stabilized seamless single wall extruded nylon tubing, available in sizes 1/8 (-2), 5/32 (-2.5), 3/16 (-3), 1/4 (-4) and 5/16 (-5).
This tubing conforms to SAE specification J844 type A.
The A refers to non-reinforced tubing.
Temperature Range: -40°F to +200°F (-40°C to +93°C).
Maximum Working Pressure: 150 PSI.
Meets D.O.T. FMVSS 106 (Sizes 2 and 2.5 not listed in FMVSS 106).
The sizes that I typically order are:
PFT-4A (1/4) / Nylon air brake tubing black @ $.47/ft. I buy 10' at a time or more
PFT-2.5A (5/32) / Nylon air brake tubing black @ $.72/ft. I buy 10' at a time or more