How do I get rid of the black highlighter thing from the shell?

It should be alpha, but it must have gotten messed up somewhere. Are you using DDS files?

Nah, blending style should be additive. Black parts mean that you should use additive, which will hide it. An alpha channel isn't needed here.

EDIT:
Nevermind, I got it in the end, 3ds max needed a restart before I could add the additive shader. Thanks for the help guys