the upgraded earthing cables make a huge difference!!!!!
But if you're gonna do the job right, then do it right
Earthing... Battery... and then consider Cap and/or alternator,
simply because, if the bigger earthing cable does fix your problem, then you've just saved yourself a couple hundred $$$ and if it doesn't fix the problem.. then it's a healthy upgrade with no adverse side-effects, and once you drop in a yellow top then the upgraded earth will be worth the upgrade.
if you still need more power... then the cap/alternator will fix the problem... if it doesn't lol then you're running a lot of juice, get a truck setup

