Thank for the suggestion, MoD Inasmuch as the real PC12 has a sleak design it was probably Klause's (model and paintkit author) intension to keep his unit as clean-looking as its realworld counterpart. Also, as an AI Only aircraft, it has a simple paintkit.
The PC12 is the world most-beautiful, single-engined aircraft.
Having said all this about all that, it's simply a matter of adding a Gradient Adjustment Layer in Photoshop to get the desired result.
I purposely did not add dirt, hatch nor rivet detail as the PC12's are not visible
Thanks again for your comments. Maybe I'll post a screen after the new repaint rolls out.
EDIT
You were correct, MoD . . . it looks better. thnx