I use chalk on the first 2 work sets and the down set. First work set is left hand over, right hand under (I do this first, because I'm weaker in this position), second work set is right hand over, left hand under, then I let myself use straps on the third set to get some more work in without doing more reps one way than the other, so as to minimise imbalances. I held the bar static at the top of the very last rep at 102.5kg...not sure how long for. More time under tension, more grip work, is good. That, plus strapless RDLs and farmer's/suitcase walks and fat gripz rows should see some positive effects.