I'll post up what we did here in the shop
Stock winjet bulb and projector
Stock winjet projector with upgraded Morimoto XB35 5K bulb
Retrofitted Mini D2S projector running upgraded Morimoto XB35 D2S bulb
As you can see the stock projector doesn't come close to a retrofitted one. These are cheap Q5R replicas or knockoffs, while better then a OEM projector in the cars, and a lot better once they have a hid kit installed in them, they just don't come close to a retrofitted set.. I'll put my retrofitted setup against the shops 10 Series stock HID setup and know mine is better. I have "tuned" my set up and I run 185$ Osram 66240 CBI bulbs.. And Bulbs make a big difference.. Anyone that says a cheap 30$ kit bulb is the same as a quality ORM bulb or even the XB35 bulbs with the handmade German capsules don't know anything.. If your wanting the most out of your lights, then doing a retrofit is the way to go..