Use this exhaust system when you want to upgrade your 1999 - 2005 Mazda Miata's performance and sound. It's perfect for car enthusiasts who love a sporty driving experience. The main piping is 2.5 inches in diameter, and the tips are 4 inches. It has a cat - back layout that replaces the stock exhaust from near the catalytic converter. You can easily install it yourself, and it comes with MagnaFlow's warranties.