@Odysseus1980
My remarks:
-eliminate double black lines (engine exhaust, vertical stabilizer, cockpit windows etc.),
-clean-up that black anti-reflex patch in front of cockpit (I re-colored it and found it's some sort of random patch of pixels),
-simplify shading of the tail top (why so dark upper edge? it's one of most sun-shined parts of the plane, after all),
-add shading along the lower edge of the engine intakes and between wing and exhausts.
@Redhorse - very nice!