Hey guys the other day i picked up a pair of bbk shorti headers from a guy for like 35 bucks, think im gonna get them installed today. I see on the net is says they add 10-15 hp but i know thats usually just a ballpark to sell the item, does anyone know if thats what youll really get or is it going to be a little less. will i notice a difference in performance or sound?? thanks again