A lot of tracks have sound limits to keep the peace with the neighboring communities. You can buy a decibel meter and try it at home first, there’s apps that utilize your smart phone also. But I can tell you I have been out there with some REALLY loud cars and they were fine. 

It’s timed sessions -20 minutes - so laps depends on the track layout and how fast you are! 

Like Matt said, as many laps as you can get in 20 minutes. 

As for sound, some tracks have sound limits, some don't.  I personally enjoy the VTECH shriek of a single exhaust Honda S2000, the rumble of an STi's boxer 4 with high flow headers, and a straight piped Mustang over dinner....but some people don't.  

And they live next to a race track. 

Thanks for the replies. Also whats up that I cant reply directly to replies? But I digress. Is a fire retardant suit strictly necessary for this course? I don't mind burning with my car, lol.

It's my understanding that  it has a lot to do with the emergency response and fire suppression equipment on site.  

As to why other organizations allow them?  I couldn't tell you.  It's between the organizer, their insurer, and the track.