SoundFX™ Aluminized Steel Oval Direct Fit Exhaust Muffler (18897) by Walker®. Optional. Direct OE Replacement. 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.