I have 12" glass packs. The cops said that I have to have a muffler and a catalytic converter since my blazer is newer than 79. I was curious about the exhaust cut. I saw it on tv i think. It is a valve that when opened your exhaust goes through your catalytic converter and muffler. When you close the valve the exhaust turns off to the side before the converter and out the side and it is basically straight piped. Anybody know of any write ups on this or have any ideas for me. I wanted to get ride of my glass packs and try this setup.