Straight-through flow path. Exclusive expansion chamber dissipates annoying mid-range drone. Flows up to 201 percent better than stock. Authoritative, but never overpowering, exhaust sound. Polished-stainless steel. 2.5 inch diameter in/out. Monster Exhaust Benefits. Replacing the restrictive stock muffler with Banks free-flowing Monster muffler makes a huge difference in airflow, sound and performance. The Banks muffler has a large inlet and outlet. And in between, the exhaust flows straight through, instead of torturously winding its way back and forth inside hairpin chambers and building up back-pressure. And only Banks Monster muffler has an expansion chamber to alleviate the nasty drone that other straight-through mufflers are known for. Banks utilizes durable ceramic packing with a high temp rating so it won't degrade like fiberglass. Add it all together and you get a muffler that flows over three times better than stock and delivers a pleasing, throaty rumble! Stainless Steel Exhaust Muffler, 2.5 inch Inlet and Outlet with adapter for use with 1991-1999 Jeep 4.0L Key Features Superior Flow and Rich, Throaty Sound Straight-through flow path Exclusive expansion chamber dissipates annoying mid-range drone Flows up to 201 percent better than stock Authoritative, but never overpowering, exhaust sound Polished-stainless steel 2.5 inch diameter in/out