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Description
Flowmonster Performance Muffler 3 in Dual inlet & outlet 12599-FM 409 StainlessOverview 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. Interior construction features 3. 50 inch "straight through" perforated 409 stainless steel tube surrounded by high temperature sound absorption packing material which helps to
Overview
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.
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 MIG-welded 409 Stainless Steel material is embossed with the "FLOWMONSTER" logo on the case.
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 MIG-welded 409 Stainless Steel material is embossed with the "FLOWMONSTER" logo on the case.
Features:
- 409 Stainless Steel construction for superior corrosion resistance and good looks
- Interior construction features high-temp interior sound absorption material delivering a deeper, mellow exhaust tone
- Perforated High-Flow straight-through tube design for increased exhaust flow
- Moderate increase in interior tone over most OE mufflers
- A stainless steel performance muffler at an economical price
- Internal Design is reversible allowing flexibility to be installed in either direction
- Sold Individually
- This is a Universal Fit muffler - Not a Direct fit. Some adaption may be required for proper fitment on some applications
| Body Height (in) | 5 |
| Body Length (in) | 22 |
| Body Width (in) | 11 |
| Finish | Natural |
| Fitment | Universal |
| Inlet Connection Type | Pipe Connection |
| Inlet Inner Diameter (in) | 3 |
| Inlet Outer Diameter (in) | 3.13 |
| Inlet Position | Dual |
| Material | 409 Stainless Steel |
| Muffler Series | Flowmonster |
| Muffler Type | Absorption / Glasspack |
| Outlet Connection Type | Pipe Connection |
| Outlet Inner Diameter (in) | 3 |
| Outlet Outer Diameter (in) | 3.13 |
| Outlet Position | Dual |
| Overall Length (in) | 28 |
| Reversible | Yes |
| Shape | Oval |
| Sound Level | Moderate Sound |
| Type of Muffler | Absorption |
| Part Number | 12599-FM |
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
- To process your return/exchange, please contact us at [email protected]
- Please click here for more details>>> Return & Exchange Policy
4.8 ★★★★★
Based on 27 reviews
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Product Reviews
★★★★★ 5
Nice Sweater
Color: 01-black, Size: Large
This is a very nice sweater. It’s reasonably thick and warm. Looks nice. I like it.
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Reviewed in the United States on January 18, 2026
★★★★★ 5
Nice turtle neck sweater
Color: Royal Blue, Size: Small
It was true to size a perfect fit and the color is beautiful. Nice sweater for the amount paid.
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Reviewed in the United States on January 11, 2026
★★★★★ 5
Very good
Color: 01-black, Size: Small
It looks so good on my bf, he really like it. The quality is so perfect.
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Reviewed in the United States on January 15, 2026
★★★★★ 5
Good quality
These fit so well material is very tick nice for winter they have all different colors and it’s so comfy it’s really good value for your money for that level of thickness
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Reviewed in the United States on September 30, 2025
★★★★★ 5
Buy it
If you're looking for a comfortable thick and nice turtle neck this is the one. It's nice and form fitting nice weight to it to keep you warm. But not to thick that you cant just wear it on a regular sunny day if you wanted. The design pattern Is also very nice. Can dress it up or down. I bought the black and then immediately bought the rust orange color for my friend once he tried on mine he wanted one immediately so I gifted him one. He loves it. Definitely worth the buy. Excellent quality. I bought a Large 5"11 165lbs
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Reviewed in the United States on December 21, 2024