[jaykay]

I happen to find this:
https://www.fvd.net/us-en/FVD424049I/shifter-cable-insulation-tubing-set-numeric-racing-reduces-interior-noise-vibration.html

In case any might have a need. They don't look to have much insulating capabilities and there is no information on the I/D. The stock stuff has nice air pockets