I was looking at these:

http://www.jpcycles.com/product/450-0067

Supertrapp Slip-ons

 

Since it sounds like you've got a noise ordinance coming your way, I would stick with the SE slip-ons. The newer SE slip-ons are fairly quiet, but sound much better than stock.

I had a pair of the old style slip-ons rated for "off-road use only" on my last bike before they quit making them & they were pretty loud.

The Rush & V&H slip-ons are going to be fairly loud no matter what. I have the V&H 3" twin slash slip ons and they are somewhat loud....kind of sound like big shots. If you're concerned about noise or being too loud, I would avoid V&H & Rush. Although I love both, doesn't sound like that is what you are wanting.

 

although those are pretty expensive, i wouldnt mind those. since you can pull that end cap and basically make it louder or quieter.