All 15 top-of-the-line Power Extreme exhaust systems are 50-state legal bolt-on affairs with topnotch craftsmanship. The Greddy Exhaust Systems uses stainless steel on both outside and inside wall. Interior of the muffler is stuffed with unique 6 sided composite fiber cubes for corrosion resistance and sound resonance. To add a stylish look, the muffler comes with a 130mm or 110mm polished stainless tip depending on the application. Greddy Exhaust Systems are designed to outlast other conventional aluminized steel exhaust systems.