I use this product on my df03 and its a great upgrade, the plastic knuckles dont hold the bearings very well causing the wheels to vibrate. also after big jumps you will find that the plastic will start to strech and expand causing the bearings not to fit snug inside. this upgrade fixes the vibration and can handle the jumps.
This hop up is a good strengthening hop up for a df03.It is alot stronger than a standard plastic rear knuckle. It also has a much smoother movement as the suspension is moved up and down because of the bushing they have put inside which the shaft fits nice and snug into, whereas the old plastic one will wear out and alot of grit can get caught up between the shaft and the plastic causing bad suspension movement, and can also scratch the metal shaft.
The alloy I think is much better made than a standard plastic one because the bearings fit into this alot easier and have less play whereas the plastic one I found can have a bit of freeplay in the bearing holes.
I also like the way that it is pre-threaded to be able to screw the ball joint in straight away, I found that as a weak point ..