DJI has announced that at the end of the month they will begin shipping the F450 and F550 ARF kits with the new E300 Propulsion System. The estimates is that this combination will provide an additional 10% in performance over the prior motor/esc combination. The really good news is that the price will stay the same as previously announced. I have a set on my F550 and just upgraded my P2Z. I will be flying tomorrow and report more.