just for info guys, the rb25 that was put into r32's didnt have vvt which is why it has no lumps on it, the only physical way of checking the difference between 25 and 20 heads is by measuing the valve sizes internally(2 hard 2 do for just curiosity) - the 20 heads have smaller valves at 30mm where the 25 heads have 35mm valves which is why most use the r32 25 head for rb30det build ups, hope this helps clear up the looks of the engine.
happy driftn!!!