All standard Axle-Back and Valve-Backs may be used on NPP equipped vettes without causing a CEL. Variable Sound NPP Valve exhausts (Part # 14777 and 14776) can only be used on vettes with NPP.
C7 Corvette Sound Level Guide: Double X-Pipe (Part # 14761) when paired with an Axle-Back or Valve-Back will increase the overall sound level of the Cat-Back system. *Variable Sound Axle-Back's with NPP Valves open are similar to Xtreme, valves closed are similar to Sport
Sport Axle-Back + X-Pipe = an Xtreme Cat-Back
Xtreme Axle-Back + X-Pipe = an Xtreme+ Cat-Back
An Axle-Back (includes axle pipes) is designed for C7 corvettes without AFM valves: Z06, ZR1, and Grandsport manual. The Valve-Back (includes adapter elbows) is designed for Stingrays and Grandsport auto with AFM. If tuning or using an AFM disabler Stingrays and GS Auto can use an Axle-Back.
C7 Carbon Fiber Intake Fitment: Stingray, Z51, and GrandSport use Part # 44001 or 44001D. Z06 use Part # 44002 or 44002D.