I ran a 1521 1y on 6s in my muggy and lst2 conversions. No issues with a decent battery.
As far as setup, the stock tranny, foc installed with a tdr single speed hub and the tdr motor mount. Nothing is better. This tranny and motor layout is superior to an emaxx tranny or any center slipper/diff setup. Losi makes good stuff, use it!!!!
I was not putting lst diffs in a revo cause they sucked!!!