Do i need to upgrade my alternator and battery or just buy an amp for this sub?

You need an amplifier to get the subs working regardless. With that much power, you might need to upgrade your alternator. Try starting off with a 1.5 or 2 Farad capacitor. A capacitor is kind of like a battery that holds a charge just for your amplifiers so that they don't draw any extra power from your alternator.