I ran TXS RFL exhaust for years. A few years ago I moved into a quiet, cull de sac neighborhood. I bought quieter exhaust. Before it arrived,I went to a block party picnic and let me tell you, many neighbors were quite pleased when I told them I had ordered quieter exhaust. Then there was the lady that told me she always knew if she was running late if she heard me drive by before she got in the shower.
I think the anonymous note was actually a good way to get the message to you without calling the popo. Get quieter exhaust, or take the bus.