Cobra 4in. Twin Mufflers 6106These 4 inch round mufflers are unique on several fronts. First, the rear is finished with a rolled scalloped tip, not a simple slash cut. That rolled tip is matched with an inner core finished with the same scalloped cut. The inner tip is actually part of the constant velocity, tuned core that gives the muffler its great sound and performance. Also, there are no unsightly external screws holding in the tip or core giving the muffler a smooth