Quick Start In Harbor Side:

Go to the race type menu and press A on "Racing Line". Then, go to the performance cars and press A on the 1995 GT90 concept car. Then, go to Colonial Run and press A on Harbor Side (the first one). When in the race, as it is counting down slow the RPM gauge between 4000 rpm and 6000 rpm and you will get a boost when it says "Go".