I tried grip puppies and I did not like increased diameter but others say the work well. You can use ALL 3 methods together. Further on my 15 I also filled the mirrors with Silicone to add weight to help the bar vibration and the mirror vibration and cure an annoying squeek - but not something i would suggest as the Acid in the cure slightly attacked edge of mirror over time. Unless you put inside some balloons and fill the balloons with the silicone. Luckily on this bike no squeek..
Thanks for the recommendation on the bar ends. Mine arrived and were fitted today Before the bar ends were fitted I would get numb fingers after 30 mins. Today after 1.5 hours of riding through the Dordogeshire twisty (and surprisingly empty) roads its smiles all round. I have a set of Grip Puppies waiting to be collected in the local post office but, I'm not sure I'll need them. See how it goes after a full days riding.
Consider me a convert. Had my first ride today after fitting last week. Vibrations are all bit gone and my hands were fine after two hours.
Quick update. Just completed a 1800 mile trip having fitted the bar ends and not a single problem with tingling / numb hands. Highly recommended.
The bar ends along with some grip puppies ... 95% improvement. Some vibes still there but nothing that causes numb hands now, even after yesterdays 200 mile run.