This muffler supersedes 4ALEX1993. This muffler design was run by the entire field at the 2023 Busch Light Clash At The Coliseum race. The part number 4ALEXR1993 that is used on this muffler is a nod to our co-founder Alex the XR1 Multicore Muffler, and the year that the patent for the Borla Multi-Core muffler design was issued. 3" Center Inlet/ 3" Center Outlet 5" x 6.25" Oval x 13.5" Long Body 18.5" Overall Length. Designed for full bodied cars, but can be used on other applications. Reversible design for installation flexibility. " Patented Multicore design (6 core) for maximum low and power. Recommend for high horsepower applications. Heavy duty 16 gauge body. T-304 Stainless steel will never rust. 100% welded construction for strength. Brushed finish for sharp appearance. Can be polished to a mirror finish. High-temperature continuous-filament fiber (CFF) acoustic material for sound control. Best of all, it's made in the USA. Just what you'd expect from the world's most experienced (and most winning) exhaust brand