Nvm guys I figured it out, you have to do 2 stunts at a time with the boost non-stop without dying all the 5mins. Its because if you dont die you get more and more points for 2 stunts. At the beginning ur 2 stunts will give you around 300 points. If you keep doing 2 stunts a jump without dying with the boost, in like 2-3mins ull be getting more then 600 points and so on so on until the last minute where you will get around 900 points on each 2 stunts jump. Remember, in order for the points to increase at each jump you never have to die.
