Denso Alternator Installation

See thats the problem, The guys who have all these electrical upgrades, but old stock wiring like me. I have HIDS, MSD, Gauges and Im adding Electric fans. I want to get a better Alt. maybe even the denso since its smaller and lighter than the stock higher amp one, but I have to worry about the stock wiring dont I ? I have relays in the Hids and will in the Fans.