I used a 1" hole saw on an extension. It deepened the sound, but not quite as much as I had hoped. A couple weeks later I put another 1" hole directly above each center pipe. That made a huge difference, and since the pipes have an overhang from the slash cut, you can't see it unless you bend way down. In my opinion, this is the best way to mod the stock exhaust. It changes the sound without noticably changing the appearance.how do you knock-out the middle plug? Is that better sounding?..if I stick a pipe in the exhaust it does stop after about 8"