Starts with a 4-inch muffler body, which then is flared out at the end to 4.5-inches. This muffler is a direct replacement for the quiet and bulky stock muffler. In order to get that aggressive sound that you’ve been wanting, Cobra designed a spun, louvered core inside the muffler body. The muffler is finished off with a reverse cone El Diablo style tip, which is powder coated and machined with the Cobra logo on top.