Hi there
Got mine, its crap, won't even undo the Abarth 17mm wheel nuts, can't budge them, yet with a breaker bar they undo easy, so I just tightened them up but lightly and it cannot even remove those. It tries very hard, thrashing away and dust/rust vapors appearing but it just does not have the torque to spin the nuts off.
I'd say this impact driver is about 100-150nm maximum, I shall do more testing shortly of loosening a bolt and then torquing it until we get to the point of it failing.
Battery is a brand new 6AH Makita 18v, so not battery and had 100% charge.
AVOID!
P.S. Max nm it can remove is 150nm, just over 100lb/ft and this is on a bolt that has being undone, re-tightened so there is no corrosion etc. It tightens to around 120nm.
In short it does not even come close to the advertise 520nm, as the saying goes you get what you pay for.