Barb,

It depends on how long your headers are. Long tube headers are fine but if you are running the shorty headers that are not much longer than a stock exhaust manifold, the issue is when you shut it off. The cold/cool air coming back into the headers could warp a vlave. The long tube headers will heat the air before it reaches the valves.

At least that is what I was always told. I have had brand new engines with long tube headers run for over an hour on first fire up and never had an issue.

I agree with NTFDAY, your neighbor just does not want to hear it. But you have to live next to them. Do you really want to make them mad?