I have a few results with png8. The images still preserve a good quality, are smaller, but I wonder if I can do even better. 

In the link below I have 2 samples, png32 version (before) and png8 (after). Is it something more I can do to these files in order to get an even better result?

Test Files: http://www.sendspace.com/file/y346v3

Raiz Roland Robert