So I'm in the middle of painting one of my stock Tie/In's up into royal guard colours so I will have 2/2/2 of each paint scheme and when I asked my fiancee how it looked compared to the stock one from IA she asked why I was using white when the original was a grey or dull silver colour. I matter of factly said it was simply a white with a black wash and when I attempted to grab a card or the box the colour was also a dull grey in look. And that got me questioning myself... What is that whiteish/grey colour supposed to be?

Not sure I understand the question.

I think his question is what color are the white parts supposed to be.
I don't know, but as long as they're all uniform, I wouldn't care

I came from a gunpla background, so Im using mr colour instead of the citadel paints you guys are familiar with.

For the body, I used Mr Color 114 - RLM23 Red. The white highlights I initially wanted to use flat off-white, but I used flat white + wash instead because of a small mixup and I'm too lazy to repaint it.

Cockpit I simply left unpainted and reused the FFG original painted one.

Check out the artwork for Carnor Jax and I think you'll find it's probably your bog standard TIE fighter gray colour where it's not red. White makes too much of a contrast with the red, where the pale gray is just that little bit more subdued.

http://img4.wikia.nocookie.net/__cb20140124180804/starwars/images/9/90/Interceptor_cover_XW_MG.jpg

Thanks for the assistance much appreciated.