Snow ball effect!!

OK you guys have peeked my interest. I have always run stock fuse boxes, wiring, etc on my cars and always ran a amp meter hooked up. Have you seen improvements by bypasing the amp gauge and rewiring all that stuff? What is the deal with these relays do they boost the power or just act as a fuse? I have most of my wiring to do still and want to upgrade the charging system, electronic ing etc. Is there any place you guys know to get info on this or has it been trial and error? TKS Tom