For the starter wire use 4gauge, and for alternator you can use 8gauge. how long are you extending the wires?josh green said:I was wandering if I could use 8 guage speaker wire to run to my starter and alternator. Ground the starter to the valve cover just like my injectors are. I heard that I can pull the wires from the RSX harness and run them to the 2 slots in the fuse box. Anyone want to give me some advice?