Not my pics but check out BBQ's pics from Toy-world.com.hk, he modded the head, I dont really understand exactly what he did, but seems he push some stuff in and with some heat.
Also, he repaint the chin area making it look more lively.
Original post here https://www.toy-world.com.hk/forum/viewthread.php?tid=14371&extra=page=1&page=1
What's with all hte wrinkling around the mouth area, looks like his skin is silly putty.