The Porter Mufflers Shorty 20" Stainless Steel Packed Muffler is a compact performance exhaust muffler engineered specifically for custom builds, hot rods, and muscle cars with restricted underbody clearance. Featuring a 14" case length compared to the 20" case of the standard model, it delivers the iconic, deep Porter exhaust note while fitting tight frame pockets, short wheelbases, and custom exhaust tunnels.
Product Overview & Internal Acoustic Engineering
Like its full-size counterpart, the Shorty muffler avoids traditional fiberglass packing that burns out and creates harsh cabin drone. Instead, Porter utilizes a heavy-duty gapped steel spring core packed with high-density stainless steel wool.
This internal steel-packed design channels exhaust gases smoothly, dissipating harsh high-frequency sounds while preserving a deep, throaty rumble under acceleration. The all-steel internal core will not break down or blow out, ensuring the exhaust tone remains consistent over the lifetime of the vehicle.
Material & Construction Options
Porter offers the Shorty 20" muffler in two distinct metal alloy configurations:
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Aircraft-Grade 304 Stainless Steel: Hand-crafted using heavy 16-gauge, highly polished 304 stainless steel tubing for maximum corrosion resistance and show-quality mirror shine.
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Aluminized Steel / Ceramic-Painted Steel: Hand-crafted using heavy 16-gauge aluminized steel tubing coated in Porter's signature high-temp ceramic paint.
Key Features & Design Highlights
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Compact 14" Case Length: Reduced body size allows easy fitment in tight floor pan recesses, street rod chassis, and short tailpipe runs.
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100% Stainless Steel Wool Packing: Permanent steel packing resists blowout and thermal degradation.
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Gapped Steel Spring Core: Disperses exhaust sound waves without restricting flow or creating low-RPM interior cabin drone.
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Heavy-Duty 16-Gauge Tubing: Resists road debris damage and exhaust system vibration.
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Non-Directional Design: Allows symmetrical mounting in either flow direction.
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Handmade in the USA: Built with U.S.-sourced steel and backed by Porter's heritage of American craftsmanship.
Technical Specification Matrix
| Feature / Metric |
Technical Specification Detail |
| Manufacturer |
Porter Mufflers |
| Overall Length |
20.00 Inches |
| Body / Case Length |
14.00 Inches |
| Body Diameter Options |
3.50" or 4.00" Outer Diameter Casing |
| Available Tubing Diameters |
2.00", 2.25", 2.50", and 3.00" Inlet/Outlet |
| Material / Finish Choices |
16-Gauge Polished 304 Stainless Steel OR Ceramic-Painted Aluminized Steel |
| Internal Construction |
Gapped Steel Spring Core with High-Density Stainless Steel Wool Packing |
| Country of Manufacture |
Handmade in the USA |
Installation & Fitting Recommendations
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Joint Welding: Sized to create a slip-fit lap joint over standard exhaust tubing. Fully seam-welding the slip joints is strongly recommended over band clamps to ensure an airtight, rattle-free seal.
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Exhaust Routing: Ideal for dual-exhaust setups on early Ford street rods, classic trucks with short beds, or tight transmission crossmember cutouts.
