On Liu Kang, it's looking pretty cool so far, but I have some critiques. The abs are too wide and too sharp, he's not flexing like that normally. Even in that picture, it's not as sharp as on your model. I would tone it down a little or go 50/50 between relaxed and flexed.
He looks too wide/short, I think the sprites are throwing you off with that. They probably have some distortion, I had the same problem with Cage when tracing the sprites. I ended up finding some random pictures of other people to have a better reference, 7.5 heads tall.
I haven't posted that update, but the file is in drop box, are you linked to it yet?
His pectorals could be more inflated.
The pants have too many wrinkles and comes off looking like the wrong fabric. I think it was sweat pants, you can see him in costume here.
http://www.youtube.com/watch?v=wxuwBQ3XHF8
The shoulders could use a little fiber detail. If you sculpt on them in the direction of the muscle fibers, you'll get some of that look. Same with any muscle, like the pecs, triceps, forearms...
Check the muscle placement, overlay an anatomy drawing over the mesh to see how it matches up.
Something else, is the detail on the pans looks kind of muddy. I think you need to play around with the brush modifiers, to give you a cleaner result. Change the shape of the fall off curve, add an auto smooth, maybe use the elastic option.
