Chip tuning means that you can run your motors at highher voltage. LEGO uses 7.4V, SBrick can accept 11.8V/3A
Of course you will need an alternative power source for example:
1. disable the limitation in the LEGO battery box and use high voltage batteries.
2. use LiPo.
You can find great infos here: https://www.philohome.com/batteries/bat.htm