Be careful with exhaust system modifications. For the most part, modifying the exhaust system after the Catalytic Converter will not cause a smog check problem, except in cases where the exhaust system is modified to a dual exhaust or vice-versa. If you are simply replacing your Nissan Titan current muffler with a Magna Flow muffler, you'll be fine. If it involves any more than that, we'd we weary.
