Npg Racing is offering a OEM replacement catalytic converter section which is direct bolt-on part requires no modifications or welding. The Catalytic converter increases air flow reducing back pressure up top and is great power adder for all applications.  The metal core catalytic converter flows over 40% more than ceramic cat and is more resistant to vibration and heat. The piping and cat is 2.5" which replaces the 2.25" smaller OEM cat although the kit has the option to adapt to the stock 2.25" axle-back or 2.5" aftermarket cat-backs.