I agree with everything Sean just said, I installed my Kerker and the K&N air filter and never even touched my carbs. I was worried about running too lean, but my dyno run actually showed that I was rich. I still haven't touched my carbs other than syncing them (the brass plugs are still in place). I will be getting Sean's Muscle Kit and installing that when I have some time. Since my dyno run I have also removed the "y" piece on the top of the air box, but I really don't know if that helps or not. Some people feel it helps air-flow and other feel it actually disrupts the flow going into the carbs.... I'm not sure if I have ever seen any dyno runs to prove it either way.
You are going to like the way your Kerkers sound... hopefully your neighbors will as well!