wala naman po masama sir sa pag add ng additional grounding nang sasakyan...
so additional wires for grounding would be a simple and inexpensive upgrade...

personally i add additional grounding wires and grounding points,
but i only use OEM surplus wires na mabibili sa mga nagtitinda ng engine and wire harness...
its usually black with yellow stripes na sobrang kapal. 0 gauge ata yun. mas maganda if meh kasamang OEM battery clamps... kasi pag oem harness pure copper ang battery clamps...

pag sa mga auto supply manipis/underrated at hindi pure copper kaya malambot at mababa diameter ng strand ng wire, so ma defeat lang purpose.

gauge 0-4 would be ideal...
dagdag ka from battery to chassis, chassis to engine, bolts near the alternator housing to negative clamp.
gamit ka na lang mga copper eyelets para mai-secure.... DIY hehe...