I had asked whaat mods I could do for free and received a wealth of info. One of them was to hollow out the stock exhaust and I even got pics and links but in one of those links, it says that the California bike exhaust can not be tampered with. Can anyone clear this up for me regarding the California exhaust pipe. The end spark arrester comes off the pipe and inside I can see a large hole coming out of a block off. Do I just drill holes in this block off? Help, I hate to ruin the exhaust and do it wrong. Thanks again.