On a new gun, if your going to be using HPA you have to convert it (very easy), setup the fps (very easy), and the ROF (which can be challenging, if your going for the sweet spot)
Then you need the 3D printed nub, as stock it's not that good ... Also the stock barrel isn't that good
I know that all sounds bad, but trust me, it's more then worth it, and once set your gold