[pitaj]

That's heat shrink tubing, but we're talking about one of these:

[1]: https://www.holley.com/products/engine/engine_dress_up/hoses... [2]: https://www.oreillyauto.com/detail/c/dorman-conduct-tite/lig...

[MengerSponge]

For performance vehicles I used adhesive-lined heat shrink tubing for basically everything.

[1] Braided tubing and [2] conduit, respectively.