Kooks KO300-12 3 in. Oval Weld On Muffler 12 in. Body T304 Stainless Steel

T304 Stainless Oval Muffler Built for Weld In Performance Exhaust Fabrication

The KO300-12 is a 3 inch oval weld on muffler with a 12 inch body length, constructed from T304 stainless steel for long term durability in high performance exhaust systems. The oval body profile of this muffler is a key advantage for custom exhaust fabrication on vehicles where ground clearance, undercarriage packaging, or spare tire well access makes a round muffler body impractical. Oval mufflers deliver the same flow capacity and noise reduction as round equivalents at a reduced vertical height, opening up routing possibilities that would otherwise require routing around obstacles or elevating the exhaust system unacceptably.

Kooks builds the KO300-12 with the same T304 stainless used across their header and exhaust product line, ensuring the muffler holds up to the thermal and chemical exposure of a performance exhaust environment without rusting or deteriorating. The 3 inch inlet and outlet keep full tube diameter through the muffler for unrestricted flow, and the weld on construction creates a permanent, leak free installation when paired with clean TIG welds. Whether you are building a complete custom exhaust or replacing a muffler in an existing 3 inch system, this muffler provides a quality Kooks option in a compact oval form factor.

Key Features

• 3 inch inlet and outlet for full diameter flow in 3 inch exhaust systems
• 12 inch body length for balanced noise reduction and flow
• Oval body profile for tight packaging and improved ground clearance
• T304 stainless steel construction for corrosion resistance and longevity
• Weld on installation for a clean, permanent exhaust system connection
• Suitable for custom exhaust fabrication on performance vehicles

What's Included

• 1 x 3 inch oval weld on muffler with 12 inch body

Specifications

Frequently Asked Questions

What pipe size does this muffler require?
This muffler has 3 inch inlet and outlet connections, designed for installation into 3 inch exhaust systems.

Why choose an oval muffler over a round one?
The oval body shape provides a lower vertical profile than a round muffler of comparable volume. This is beneficial on vehicles where ground clearance is limited or where undercarriage packaging makes a full round body impractical.

How long is the muffler body?
The muffler body is 12 inches long. This length provides a good balance between muffler volume for sound attenuation and overall exhaust system length.

How is this muffler installed?
This is a weld on muffler. It is welded into position in the exhaust system by welding the inlet and outlet to adjacent 3 inch exhaust tubing.

What material is this muffler made from?
The body is T304 stainless steel, which provides excellent resistance to exhaust corrosion, road salt, and thermal fatigue.

Can I use this muffler on a dual exhaust system?
Yes. For a dual exhaust layout, two mufflers would be used, one per side. Each is sold individually.

Will this muffler work with clamps instead of welding?
This muffler is designed and rated as a weld on component. While exhaust clamps can be used temporarily, welded connections provide a more permanent, leak free, and vibration resistant installation.

How loud is this muffler?
Sound output depends on the rest of the exhaust system configuration, engine displacement, and vehicle. The 12 inch body provides moderate sound attenuation. Customers building quieter systems may prefer a longer body muffler.

Is this muffler compatible with Kooks header systems?
Yes. This is a 3 inch universal muffler that integrates naturally with Kooks 3 inch header and exhaust systems.

Installation Instructions

1. Allow the exhaust system to cool completely before beginning fabrication work.
2. Determine the mounting location, ensuring adequate clearance from the floor pan and other undercarriage components at the oval body height.
3. Cut the exhaust tubing at the inlet and outlet positions, accounting for the 12 inch body length plus weld joint allowance.
4. Position the muffler in the desired orientation, noting inlet and outlet flow direction.
5. Check orientation to confirm the oval body clears all obstacles with the vehicle at ride height.
6. Tack weld at multiple points before completing full circumference welds at inlet and outlet connections.
7. Use T304 compatible filler for TIG welding to match the muffler material.
8. Inspect welds and check for exhaust leaks after the first startup.

Prop 65 Warning

WARNING: This product can expose you to chemicals including Chromium and Nickel, which are known to the State of California to cause cancer, birth defects or reproductive harm. For more information go to www.P65Warnings.ca.gov.