70db where? outside the property? Most tracks run a muffler of 100db at 100 yards away from the car. To be quite honest, I've heard muffler test on a sprint car that had them quieter than a street car (Not that I want to watch that quiet of racing).

Edgewater lies in the Great Miami River valley. I used to live 8 miles north and it was quite common to hear the dragsters. If they had jet cars it rattled the windows of the house. I remember one night the BEACH BOYS played in the late 70s early 80s and a South to North Wind was blowing, I heard most of the concert 8 miles away at my house sitting on the front porch.

I don't see this hurting too much, A lot goes into how long a show runs, A good track that a lot of spins don't happen, Good wrecker crew, keeping a extra ambulance at the track and most nights 11pm wouldn't be a problem.