Los Santos Forum
The Los Santos Forum is the main stadium servicing Los Santos, and is located at the southeast end of the city, in the Playa del Seville district. It resembles a miniature version of the Great Western Forum (a.k.a. the Los Angeles Forum) in the city of Inglewood.
Here is one of the stadium races calls 8 track to pass this mission you have to win in 1st place, after that a Monster and the Hotring Racer will spawn near the entrance.