This Cat-Back system uses a high-flow straight through muffler designed to deliver a deep, sporty tone from your 1999-2005 Mazda Miata with 1.8L engine. It produced an extra 4 HP and 3 lb-ft of torque at the rear wheels. This system is constructed from 304 stainless steel providing maximum durability. It uses 2.25 inch tubing and a polished 3.5 inch tip. Simple installation is made possible by using the factory mounting points. All this provides you with a system that offers great looks, awesome sound, and maximum performance.