Let me introduce Mistress: Jim Marsden’s Off-Road Beast, the latest race car from Gigglepin Racing. Grab a coffee, a beer, or simply take a seat and discover all the secrets behind Jim Marsden’s newest love—built around a Miller Motorsports chassis and powered by a high-performance 625-horsepower LS7 V8.
Mistress: Jim Marsden’s Newest Love
Off-road legend Jim Marsden is back with a new race machine: Mistress. Built on a cutting-edge Miller Motorsports chassis and powered by a roaring 625-horsepower LS7 V8, this beast is set to take on the toughest Ultra4 challenges. After the success of Bad Penny, Mistress steps in to continue Marsden’s legacy of innovation and domination in the world of extreme off-road racing. Here’s an exclusive look at the details behind Jim Marsden’s newest love.
Jim Marsden: A Legend in Off-Road Racing
Jim Marsden hardly needs an introduction. He started racing in 2000, improving with every competition. Today, he is the most successful off-road driver in Europe, boasting over 70 international podiums and more than 30 titles to his name—from Ultra4 Europe to the Rallye Breslau. When he’s not racing, Jim is a motorsport ambassador at various shows and events, representing the brands that support him and his team. He is also one of the official commentators of the world’s toughest one-day off-road race, King of the Hammers in California, as well as the Ultra4 National Finals in Reno, Nevada, and major events like the MINT 400 in Las Vegas.
Off-road racing is Jim Marsden’s life. He is the founder and owner of Gigglepin 4×4 and Gigglepin Winches, drawing from his vast experience to develop innovative, market-leading products such as the GP100 winch.
After bringing success to Little Lady and Bad Penny, Jim Marsden now has a new race car—and today, I’m introducing you to his latest machine: Mistress.
A Miller Motorsports Chassis for Mistress
Jim Marsden is no stranger to Erik Miller, a two-time King of the Hammers champion and Ultra4 National Champion. “In Ultra4, it’s the best car in the world and the most technologically advanced,” Jim says of Miller’s race car. That’s why he chose a Miller Pro chassis as the foundation for his new build.
While recent Ultra4 vehicle development has leaned heavily towards IFS (Independent Front Suspension), with many recent KOH winners running IFS rigs, there are still strong advocates for hard-axle setups—among them Erik Miller, Randy Slawson, and Jim Marsden himself. Reliability and lower maintenance were key factors in Marsden’s decision, as these attributes are crucial for finishing races.
The Miller Pro chassis is available as a kit, which Jim purchased and had assembled by Black Bird Industries. Along with the main kit, a variety of additional parts are available, including engine and transmission mounts, suspension links, skid plates, and side panels—offering a comprehensive solution for those who prefer a pre-configured setup rather than building everything from scratch.
Jim added his own custom touches, such as the steering column (Mistress is the only right-hand-drive Miller Motorsports chassis in the world), the choice of a 4L80E transmission instead of the more commonly used TH400, and the Spidertrax Pro Series 4″ axles.
A 625-HP LS7 V8: The Beating Heart of Mistress
Under the hood, Marsden has installed a 7.0L LS7 V8, producing 625 horsepower. While it can be pushed to 700+ HP, Jim insists that “it’s not necessary.” The engine is managed by a Holley ECU, which controls the engine, dashboard, and transmission. This eliminates fuses and relays, with everything electronically managed—including the ability to program multiple tuning maps.
Paired with the LS7 is a 4-speed 4L80E transmission and a latest-generation Atlas II transfer case from Advance Adapters.
Axles, Steering, and Suspension
Mistress is built for extreme conditions with Spidertrax 4″ axles, using FK Rod Ends spherical joints. The front wheels have an impressive 53° steering angle, with 40-spline front shafts and 45-spline rear shafts. The steering system comes from D&G Tuning.
For differentials, the front features a TubeWorks housing with a Detroit Locker, while the rear is a GearWorks unit with an ARB air locker.
As always, Marsden stays loyal to FOX for his suspension setup. Mistress features coilovers and bypass shocks from FOX, with 2.5″ bypass and 2″ coilovers in the front, while the rear setup is even more robust with 3.5″ bypass shocks—the same configuration used by Erik Miller. These custom factory bypass shocks have larger tubing and a specific valving system tailored to Mistress.
Key Features of Mistress
- Cabin & Dashboard: Optimized for performance and ergonomics.
- Transmission: Custom 4L80E gear selector.
- Engine Bay: Positioned at the front for optimal weight distribution.
- Cooling: The radiator is mounted behind the cabin.
- Wheels & Tires: Raceline wheels and Maxxis tires.
- Winch: Gigglepin GP100, engineered for ultimate recovery performance.
