[donboscow]

Yeah, I get the R&D part, what I want to know, what specific improvement here does the R&D here contribute to?

[coldtea]

"the use of particular materials, precision engineering, and slim custom components"

All of the above require R&D. Techniques for unibody construction for example required a lot of R&D in machining parts, precision opening of ports, and so on.

[kingkongjaffa]

The hard part is also not doing it once really well, it's doing it 100's of millions of times also really well.