Check the listing for details. 12599-FM FLOWMONSTER 409SS OVAL CASE ABSORPTION MUFFLER. Color: Stainless Steel, Condition: New, Made in CN. Listed at 101.95 USD. FLOWMONSTER MUFFLER - 3.00 DUAL IN/3.00 DUAL OUT - 5.00 x 11.00 OVAL CASE - STRAIGHT THROUGH PERFORMANCE - MODERATE SOUND - 409 STAINLESS STEEL. 1 The Flowmonster series of absorption style mufflers deliver a moderate tone for the enthusiast looking for a deeper, more aggressive exhaust note than most OE (Original Equipment) mufflers, unlike the racey exhaust note associated with "chambered" style mufflers. 3 Interior construction features 3.50 inch "straight-through" perforated 409 stainless steel tube surrounded by high-temperature sound absorption packing material which helps to deliver a deeper, mellower exhaust note. The internal design is reversible allowing the flexibility to be installed in either direction to best accommodate fitment with the intended vehicle. The fully.