I forget how they work. You can add or subtract to change the sound and performance. My wife's is set up to be more quiet. She didn't want loud ,but wanted performance and to be able to add bags. My Deluxe has V&H and I like my sound much better.
I added what the CS guy said to start off with and see how I liked it. I wanted lower noise on longer rides. I had previously tried Rush and rhinehart mufflers on the stock pipes. To me they were both too loud.