I have the aluminium Domino bar ends - they seem to do the trick. You can get them almost anywhere, Maniac Trials for example. If you can make sure that they cover the thicker end of your grip (where you lock wire the grips on), as the first ones I had didn't, and the grips still got butchered. I have found that the Renthal soft compound trials grips seem to be the best in wet and muddy conditions, though you probably don't get it as wet and muddy as NZ in Texas.