Black Duck Stainless Steel slip-on mufflers are designed in Barcelona and made in Spain using state of the art materials and race-proven advanced techniques to maximize engine power and efficiency. These 4" (10cm) diameter mufflers slip straight onto the stock headers and leave the passenger pegs in the original position. Mufflers feature permanently mounted dB-killers. For track use, these components can still be removed, but doing so requires permanent alterations to the exhaust system. This ensures a deep, throaty sound, but voids the E-approval.