PERRIN mufflers have a true 3" internal diameter for uninterrupted exhaust flow. PERRIN mufflers and flange connections are 3" throughout the entire length, not necked down, for ultra smooth transitions throughout the system. PERRIN Exhaust systems feature high tech v-band clamps for a perfect exhaust connection. V-band clamps are designed to hold hundreds of pounds of pressure and do so without the need for a gasket! This connection allows for a precise repeatable joint with the ability to rotate each joining connection. This allows for easier installation and alignment adjustments for a perfect fit every time.