Just been debating this in a different thread! It's my opinion that 6s is to much for the 1y, It can handle it yes but for how long and the temps will be higher than ideal and generally the optimal operating range is 35k +/- a few thousand. 5s is out of the optimal range in my opinion, the 1y is ideal for 4s. A 2.5d is better on 5-6s, it's actually freakish on 6s! At 25MPH it will still flip over if I punch it. This is all just my opinion.