why wouldnt you pass CA smog with a hole in your muffler? Your muffler has no bearing on smog. I work for CARB, and all they do is put a sniffer in your exhaust like they do when you are tuning to look for certain things while tyhe car is moving. If you have a bad cat then you have a problem,. Just a hole in the muffler should be fine. Go ask the techs before you smog. Tell them it has no effect on emissions.