2018+Jeep Wrangler MRT King of the Hill JL Axle Back Performance Exhaust System 90R137

MRT 304 Stainless Axle-back: 2018+ Jeep Wrangler JL #90R137

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2018+ Jeep Wrangler MRT King of the Hill JL Axle Back

Retail Price: $239.99

You Save: $

Loudness: 9 Drone: 3 Performance: 8

Application:Application: 2018+ Jeep Wrangler JL 3.6L and 2.0L 4XE (2-Door and 4-Door)
Tune: None Required
Time to Install: 60 Minutes

Choose your options:

Available Options:

Polished T304 SS Tips - Standard

Item Code: 90R137

Usually Ships in 1 to 2 Business Days

This product qualifies for FREE SHIPPING!

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Jeep Wrangler JL King of the Hill Axle-Back Exhaust System

Part Number: 90R137
Application: 2018+ Jeep Wrangler JL 3.6L and 2.0L 4XE (2-Door and 4-Door)
Installation Time: 60 minutes
Warranty: Limited Lifetime

Maximum Sound and Performance for Your 2018+ Wrangler JL

Transform your 2018+ Jeep Wrangler JL with MRT's King of the Hill axle-back exhaust system, the loudest and most aggressive exhaust option in the MRT lineup. Engineered specifically for off-road enthusiasts who demand commanding presence both on the trail and on the street, this performance exhaust delivers deep muscle car sound without excessive drone.

Constructed from premium T304 stainless steel with mandrel-bent 2.5-inch tubing, the King of the Hill system maximizes exhaust flow while featuring a turndown design for optimal ground clearance during extreme off-roading. Whether you're conquering rock trails or cruising the boulevard, experience the perfect combination of aggressive exhaust tone, enhanced performance, and off-road functionality.

The MRT Wrangler King of the Hill JL Axle-Back system has a loud, deep muscle car sound and is handcrafted in corrosion resistant T304 Stainless Steel. Base systems include T304 polished SS 2.5" mandrel bent tube. There is a Turndown tip on this system for optimal ground clearance. This system is engineered for the best sound to match your Jeep and provides increased performance from increased exhaust flow. It was designed with off-roading in mind. King of the Hill is the loudest MRT exhaust with enough elevated sound to Get Noticed, plenty of opportunity to Feel the Performance and packaged in a design without excessive drone.

Application: 2018+ Wrangler 3.6L, 2 and 4 Door.

Hear the Difference

How does it sound? The MRT Wrangler MRT King of the Hill JL Axle Back #90R137 has an aggressive Get Noticed exhaust note that is present at all times.
Is there drone or resonance? The drone is noticeable but tolerable.
What if I step on it? Wide-open throttle brings out a more lively attitude with more exhaust sound, bite, and a deep growl.

Are you located close to Plymouth, MI and need your MRT aftermarket exhaust installed? Call MRT at 734-455-5807 to make an appointment today!

Technical Specifications

Product Features

Material: Corrosion-resistant T304 stainless steel construction
Tubing: 2.5-inch mandrel-bent for maximum flow
Design: Straight-through configuration with turndown outlet
Tip Style: Turndown 2.5-inch T304 stainless steel pipe (no protruding tips)
Manufacturing: Engineered & Assembled in Plymouth, Michigan
Hardware: Complete installation hardware included
Finish: Polished T304 stainless steel

Performance Ratings

Loudness: 9/10 - Aggressive, attention-grabbing exhaust note
Drone: 3/10 - Noticeable but tolerable cabin resonance
Performance: 8/10 - Significant gains in flow and power
Tuning Required: None - direct bolt-on upgrade

Performance Benefits and Sound Characteristics

Enhanced Exhaust Flow and Power Gains

The King of the Hill axle-back system features a straight-through design that significantly reduces exhaust restriction compared to the factory muffler. The large 2.5-inch diameter tubing allows exhaust gases to exit more efficiently, reducing backpressure and extracting additional horsepower and torque from the 3.6L Pentastar V6 engine.

With a performance rating of 8 out of 10, drivers experience noticeable improvements in throttle response and acceleration across the RPM range. The reduced restriction allows the engine to breathe more freely, optimizing power delivery for both trail performance and highway passing situations.

Aggressive Sound at Every RPM

Idle: Deep, commanding presence that announces your Jeep's personality
Cruising: Noticeable but tolerable exhaust note with manageable drone levels
Acceleration: Lively, aggressive growl that intensifies with throttle input
Wide Open Throttle: Full muscle car roar with deep, powerful exhaust tone

The King of the Hill delivers consistent performance sound that remains present at all driving speeds and conditions, giving your Wrangler JL the aggressive character that matches its off-road capabilities.

Warranty

Engineered, Designed and Assembled in Michigan

Every King of the Hill exhaust system is manufactured at MRT's Plymouth, Michigan facility, ensuring consistent quality control and attention to detail. The flexible manufacturing process allows MRT to maintain strict standards for welding quality, fitment precision, and overall construction that mass-produced imports cannot match.

Limited Lifetime Warranty Protection

MRT backs the King of the Hill exhaust system with a limited lifetime warranty, covering defects in materials and workmanship for as long as you own your Jeep Wrangler JL. This warranty reflects MRT's confidence in their premium materials, manufacturing processes, and American-made craftsmanship.

FAQs: Performance Exhausts for 2018+ Jeep Wrangler JLs (2-door and 4-door)

1. Will the King of the Hill exhaust fit both 2-door and 4-door Wrangler JL models?

Yes, the MRT King of the Hill axle-back exhaust system (Part #90R137) is engineered to fit both 2-door and 4-door 2018+ Jeep Wrangler JL models equipped with the 3.6L Pentastar V6 engine. The system features a direct bolt-on design that connects to factory mounting points on either body configuration. This exhaust does not fit Wrangler JK models (2007-2018) or Wrangler JL Rubicon 392 models with the 6.4L V8 engine, which require different exhaust configurations.

2. How loud is the King of the Hill compared to other MRT exhaust systems?

The King of the Hill is the loudest exhaust system in MRT's Wrangler JL lineup, rated 9 out of 10 for loudness. This represents maximum aggressive sound output designed for enthusiasts who want commanding presence and attention-grabbing exhaust tone that is always on. If you prefer a more moderate sound level, MRT offers quieter options like the Trail Rated(loudness rating 5/10) or Streetfighter (loudness rating 7/10). Despite its aggressive sound, the King of the Hill maintains tolerable drone levels rated at 3/103. Why does this exhaust have a turndown design instead of traditional tips?

The turndown design is specifically engineered for off-road functionality and maximum ground clearance. Traditional exhaust tips that protrude behind the bumper are vulnerable to damage from rocks, obstacles, and trail hazards during serious off-roading. The turndown configuration routes exhaust gases downward and away from the rear of the vehicle, eliminating this vulnerability while maintaining optimal ground clearance for extreme terrain. This design choice prioritizes durability and off-road performance without sacrificing the aggressive sound signature that defines the King of the Hill system.

4. Can I install the King of the Hill exhaust myself, or do I need professional installation?

The King of the Hill axle-back is designed for straightforward DIY installation and typically takes 60 minutes using common hand tools like wrenches, sockets, and jack stands. All necessary mounting hardware is included, and the system bolts directly to factory connection points without requiring welding or modifications. Most Jeep owners with basic mechanical skills can complete the installation in their garage or driveway. However, if you prefer professional installation and are located near Plymouth, Michigan, MRT offers installation services at their facility. Call 734-455-5807 to schedule an appointment.

5. Does the King of the Hill exhaust require ECU tuning to work properly?

No ECU tuning or computer modifications are required for the King of the Hill axle-back exhaust system. This is a direct bolt-on performance upgrade that works perfectly with your factory engine computer and fuel mapping. The exhaust system delivers immediate sound and performance improvements without triggering check engine lights or requiring additional calibration. The straight-through design and optimized tubing diameter provide enhanced exhaust flow and power gains while maintaining compatibility with all factory emissions equipment and sensors, making it a hassle-free upgrade for your Wrangler JL.

Ready to upgrade your Wrangler JL? Order the King of the Hill axle-back exhaust today and enjoy free shipping. Questions? Call 734-455-5807 or use live chat during business hours.

Installation and Fitment

Can I install this myself? Yes, MRT engineers this Premium Exhaust System for a simple do-it-yourself (DIY) installation.

How long does it take to install? Installation time is about 1 hour and requires only common hand tools.

What is included? All necessary hardware included.

Note: No products will be accepted for return after installation has occurred.

Simple DIY Installation Process

MRT engineers designed the King of the Hill axle-back system for straightforward do-it-yourself installation in approximately 60 minutes. The bolt-on design requires only common hand tools, making it accessible for backyard mechanics and weekend DIY enthusiasts.

All necessary hardware is included with your purchase, and the precision-engineered fitment ensures proper alignment with factory mounting points. No welding, or modifications are required for installation on 2018 and newer Jeep Wrangler JL models equipped with the 3.6L V6 engine.

Compatibility: Both 2-door and 4-door Wrangler JL models (2018+)
Engine: 3.6L Pentastar V6
Required: None - direct bolt-on installation
Tools Needed: Basic hand tools (wrenches, sockets, jack stands)

Professional Installation Available

Located near Plymouth, Michigan? Schedule professional installation at MRT's facility by calling 734-455-5807. Expert technicians can install your King of the Hill exhaust system while you wait, ensuring perfect fitment and optimal performance.

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