Using Your Marbles
You can use a couple of marbles to block the air injection hoses located at the very front of the front rocker cover and the very rear of the rear rocker cover to help reduce or even eliminate the "popping" heard on decelleration.
If you look from the right side of the bike you will see a hose coming out of the rocker at the locations described above. Remove the hose (held in place with a spring clamp) shove a regular marble up the hose far enough so you can clamp the hose back on the tube.
Doing this cuts off the air injection to help burn off unburnt fuel. If you do not do this you may get lots of poping on decel normally not heard because of the stock mufflers (though some of us here it even with stockers). Some with newer models (2008 and up) have said this did not work as well or possibly not at all on their bikes.