SoundFX™ Steel Oval Direct-Fit Aluminized Exhaust Muffler (18106) by Walker®. Optional. Muffler Inlet Diameter: 2.25″. Muffler Outlet Diameter: 2.25″. Muffler Body Length: 22″. Muffler Overall Length: 30″. Muffler Configuration: Offset – Centered. This muffler is the right choice if you opt for quality acoustics and performance. Walker offers 100% aluminized steel SoundFX™ Mufflers with direct fit and universal fit options available, both designed to maintain a quality appearance and agreeable exhaust tone.