SSj4 is a real stage, there is no other physical appearance that they could give with the original ssj forms, theres:
regular (changed hair, green eyes)
ultra (big with hair long..but slow as heck)
x2 (slightly bigger muscle wise, compared to ssj1, changed hair but still about same height)
x3 (long hair, so long you could step on it while walking..almost.. head shape changes to give a more "menacing look". in the japanese version the voice doesnt change, but in the american version it does... weird.....)
I already saw it in english, the tapes are up to the episode when buu uses the genocide attack and ************ (i dont want to be a punk and tell you..but your jaw is gonna hit the floor when you see it.. lets just say.... a hole-in-million... if you didnt get it then im sorry for you)
goku did ssj3 a loooooong time ago tape wise, hes back with pre-mystic gohan
if you watch the japanese episodes you will see the heck this mystic crap everyone is talking about, is.