impressive is an understatement.

its a pity most of the depth is lost on the sphere =/
early wips made me think you were going to go mad with the chrome effect, was almost disappointed that you didnt.

keep the mapping in mind as you're laying things out. the vents would have been more impressive if they were a bit further back or closer to the face.
would exaggerate the depth and work darker on the mouth piece more, it gets a bit lost on the sphere
sharpening up a few of the highlights might not hurt either.

classy work though