When I installed my TWM shift knob I noticed that the ring that was in the boot from the factory was too big.
So I set out to find a solution.
I didn't have to look far as I had a 2 liter bottle of soda sitting on the counter.
Step one. Cut the soda bottle along the red lines that I have here:
That will leave you with this piece:
Then take your boot and cut the zip tie holding the factory ring in place:
Zip tie the smaller ring in place:
And there you go. You now have a better fit for the shift boot.