The following description is an example of a cheap adaptation that works for me.
At one of the local auto parts stores I noticed that there was a selection of foam stripping which had an adhesive backing, similar to the stuff you would use to seal around the edge of a draughty door.
This stripping was available in varying widths and thicknesses, and was sold by the meter.
I used some to weather seal the top and lid closure of one of my trailers , and I had some left over.
Thinks I thought , the ST handle bars could do with some cushioning, and I thought what would it be like if I was to spiral wrap some of that stuff around the hand grips in a similar way as to what is on the handle of the tennis racket or the golf clubs.
I tried that and I was pleased with the result, but the surface was very soft and spongy and looked as if it would quickly soak up some water if exposed to rain or heavy dew.
My solution to that was to add a couple of layers of a good quality pvc. black electrical insulation tape wound fairly tightly in a spiral pattern in the opposite direction to the foam.
This compressed the foam a little and made a very comfortable improvement in the feel of the hand grip for me.as well as slightly increasing the handle diameter which for me was a definite plus.
The finished look could almost be as factory.
A cheap mod but it worked for me.
Cheers to all,
Winston66