My opinion, the head is not too small. You have to be holding P/CP in your hands... if anything Sunstreaker/Sideswipes's heads might be too big

I've no complaints on this guy other than the screws appearing on Punch's mode.
I think TFCC did a bang up job.
WARNING: Be careful when sliding the car hood/engine bay forward during transformation.. Punch's rub sign can get stuck and crumple up. Lift up just slightly on the roof/windshield and then pull forward.