All standard Axle-Backs may be used on NPP equipped camaros without causing a CEL. Variable Sound NPP Valve Axle-Back (Part # 14789) can only be used on camaros with NPP from factory.

Camaro Sound Level Guide: Double X-Pipe (Part # 14788) when paired with an Axle-Back will increase the overall sound level of the Cat-Back system. *NPP Valve Axle-Back (Part # 14789) is similar to Xtreme with valves open, Sport when closed. 
Sport Axle-Back + X-Pipe = an Xtreme Cat-Back 
Xtreme Axle-Back + X-Pipe = an Xtreme+ Cat-Back

Camaro Double X-Pipe (Part # 14788) fits Manual Transmission vehicles. Automatic Transmission vehicles will require an AFM tune because the X-Pipe does not contain AFM 4-Mode valves.

Seamlessly connect to your CORSA Cat-Back or X-Pipe (Part # 14788) by purchasing: Long Tube Headers with Connectors (Part # 16122).

For custom applications, Long Tube Headers (Part # 16022) are available. CORSA Exhaust Connection Pipes (Part # 16027) are designed to connect CORSA Lube Tube Headers (Part # 16022) with existing CORSA Cat-Backs and X-Pipe (Part # 14788).