The MBRP S6150409 4 Inch XP Series Turbo-Back Exhaust System is the perfect way to upgrade your 1989-1993 5.9 Cummins. Made of T409 stainless steel, this exhaust system is built to last with a lifetime warranty. It features a 3.5" turbo downpipe and 4" exhaust piping for maximum flow and performance. The mirror polished, T304 stainless steel exhaust tips give your truck a look of sophistication and power. This system installs easily with common hand tools and gives your Cummins a rich, mellow exhaust note that is sure to turn heads.