You're probably right about the F6 being put over something like conduit. It certainly looks much nicer in the catalog than in real life.
Here's some more pics of the Insultherm. All these, along with the ones in the earlier pics were built by a mate of mine who does custom pigtails and harnesses. The first one is a custom harness for the HKS Twinpower DLI, and he builds it to any length required, and will install any type of mating connector on the end, or leave it free, the 2nd one is a little harness for 9006 type HID's (I'm not sure this is the same type Insultherm - it might be another type of high temp sleeve), and the last one is a Bosch injector harness, showing a good method of breaking out from the main run.
He slices into the main run with an X-acto knife, fishes the breakout conductors through the slice, cuts them to required length, gets the crimps on, then seals the breakout area with a bit of silicone, and puts heat shrink over it. There's also an internal ty-rap that can't be seen to keep the breakout from pulling out.
Not trying to be a salesman for this guy, but he really does nice work and is VERY reasonable. Plus, all the dealings I've had with him have been by email, and it's worked out perfectly. I send him a wiring diagram, or schematic how the harness needs to be wired, plus a mechanical diagram, showing the lengths and where the breakouts need to fall, etc. and he builds it.
He also installs sleeves on existing harnesses, so if you don't want to mess with removing your connectors, and run the risk of damaging them, he can do that for you. He has good sources for the different connectors also, so if some of yours are already brittle and broken, he can replace them.
If you want to contact him, PM me and I'll give you his details. Harnesses aren't heavy at all, so it might be very reasonable for you from Oz, especially with your strong $$$ now