Which parts of MBA-13" mid-2011 can be upgraded? Which parts (if any) in Macbook Air 13" mid-2011 can be upgraded to either:


an original part from a later version of Macbook Air/Pro
or a third-party component which has a better performance/extra features?


Which are those replacement work really well (eg with no compatibility problems; last at least as long as the originals etc)?

E.g.: CPU, SSD, RAM, main board, wifi/BT card, speakers, USB 3.0, camera etc.
Here is what I found so far:


wifi: upgradable to 802.11 AC, with third-party QuickerTek QCard2 (manufacturer gives dimensions: V1= 18.07mm x 39.9mm, but contradicting answers on whether it's compatible with MBA2011 13"). I asked for feedback on it in a separate question; haven't tried it myself yet)