My favorite place to bash is at a secret place know as the "bike jumps". Its located at the near the end of Aliso Creek in Mission Viejo. It was made by some highschoolers for riding bikes but it serves just as well as a bash center. There is another as mentioned by..."jdwebmaster"... it is in a gated community called Quail Run. It's more of a smaller track (perfect for 1/10th scale and smaller) but is great just to practice.

Hint Hint... to get into the gated community wait for a car to ahead of you!