An annular disk comprises a front surface, a rear surface, an outer surface, and an inner surface. The front surface has a front opening within a front plane. The rear surface has a rear opening within a rear plane. The rear opening, which has a diameter that is smaller than a diameter of the front opening, communicates with the front opening to define a bore for guiding an exhaust stream flowing from a turbocharger to an exhaust outlet. The outer surface connects the front surface to the rear surface and includes an outer angled portion, an outer radial portion, and an outer axial portion. The inner surface includes an inner angled portion, an inner axial portion, and an inner radial portion extending between the inner angled portion and the inner axial portion. The inner radial portion is configured to obstruct a portion of the exhaust stream to increase back pressure.