This all-new buggy re-introduces the forward-swept front end and rear-mounted shock configuration of the original Stealth car, optimized with the new co-planar Ackermann steering geometry. This new suspension design provides maximum front-end clearance and minimizes bump-steer while maintaining correct buggy Ackermann angles. Trailing front axle or optional inline steering blocks can be used to adjust steering response.
The B4 chassis provides a super-low center of gravity by lowering the motor, battery, wing and even the shock mounting positions, enabling much higher cornering speeds and stability during jumping and through bumpy sections of the track. The adjustable-angle rear wing mounts and even the transmission case are now integrated into the chassis/suspension structure. The symmetrical suspension arm design has all four arms being the same length, and "captured" hinge pins so that no e-clips are used.

The transmission has also been optimized into an ultra-compact package, and now uses the same 2.6:1 higher torque-capacity differential as the RC10GT. A double-sided slipper assembly (first prototyped by Team Associated in 1989) has been designed with higher torque capacity, easier assembly, and lower rotating mass than comparable double-sided slippers. This provides a finer adjustment range and more efficient slipper operation.

The B4 uses new offset-front wheels and "wide-body" front tires. The rear wheels are now interchangeable with other manufacturer’s buggies, enabling pre-mounted tires for standardized "spec" class racing to easily be used. The B4 is topped off with an all-new, super low-profile body and adjustable rear wing, providing a sleek, aggressive look on the track.