At all major Bay Area raceways a noise limit is published, and exhaust limits are either stated or implied (i.e. limiting to 90dB requires a muffler).
Sonoma Raceways - 103dB at 50ft.
Thunderhill Raceways - 103dB, mufflers required.
Laguna Seca - 90dB, with rare exceptions.
Antioch - 95dB at 100ft.
Ocean Speedway - 90dB at 100ft.
Petaluma Speedway - 95dB at 100ft, mufflers required.
Stockton 99 Speedway - 95dB, "exhaust must be turned down or out".
Measurement techniques vary; Laguna Seca is especially hostile to noise to the point that some stock exhaust systems do not comply from factory (i.e. Subaru WRX STi); Stockton 99 buries the limit deep in the fine print viewed by racers; Nascar is difficult to host as their cars can reach 130dB; enforcement may be more or less strict; it's possible there are smaller local tracks I don't personally know about that aren't listed here (I'm more familiar with North than East or South, for example).