Where is the best place to race go-karts in the Philly, South NJ, DE area?

I am not talking about the kind for little kids, im talking about gas powered 40+mph karts...indoor or outdoor|||I would check out New Jersey Motorsports Park at www.njmotorsportspark.com. I don't know if it has opened just yet, but log on to the web site and take a look. It's supposed to be a world-class facility for all forms of racing.