So Xur is back and with him, aside from the exotic gear, are sparrow upgrades that I have been eyeballing for a bit now. Now I have bought one (the Plasma Drive) and I have a shiny new Legendary Sparrow with the speed of a falcon and the durability of a rhino. So it feels like at least. But anyways, if I was to buy another Plasma Drive, would that stack on top of my existing one making it even stronger and faster again, or would it just stay the same. Or another example would be, if I bought a Green contrail to flow behind it, would that replace the plasma drive I already have and lower the speed and durability back down, or will those stats keep and my trail will just be green instead? EDIT: Question answered. Thank you.