from wat i understand, the grounding is to improve effectiveness of ur electrical system. its performance can be obvious for old car. but for new car such as satria neo, the effect will minor because nowadays car has improve their electrical system from the factory.the concept is to make additional route for current to travel from ur electrical devices back to battery.
so, ussually the grounding cable is attach to:
1)-ve terminal on the battery,
2)alternator
3)firewall/body
4)engine head
so, gudlaq