Looking good, Joe.
Maybe bump up the highlights to give it more shape. I'd run quite a sharp highlight along the spine and up the fin. Even if the paint is quite matt, narrow radii will always give a highlight. Adding more highlight to the nose, fuse and tail bulge is going to give them more form too. Watch your cast shadows from the wing on the tank and pylon, they should probably be almost as dark as they are on the fuse, it is the same object casting the same shadow. I think the shadow on the tank needs to slide back well under the wing. Run the shadow on the pylon down from the leading edge and then run it over the tank from there. The intensity of the shadows on the fuse look pretty good to me, nice and subtle with some reflections.
I hope this helps!
Grubby.