All A'PEX exhaust systems comply with applicable emission laws since they neither modify nor relocate the required factory emission control devices; they are considered "direct replacement" parts. Such parts do not require a CARB Executive Order (EO) since they are not "add on" or "modified" parts. A'PEX exhaust systems are "functionally identical" to the OEM parts during emission tests. Sound levels are tested on stock vehicles before the product release to ensure compliance with the 95dB limit.

that is from the apexi website on the n1 exhaust system.