Ceramic core catalyst high flow replacement for the stock cat. Replace your restrictive, or worn-out cat with this high flow cat to reduce backpressure, improve throttle response and performance. Available in 2.25 to 3″ sizes for your normally aspirated, Supercharged, or Turbocharged miata. Call about the 3″ systems. They will need a special flange if mated to some turbo kits.