MR-04 Upgrade Guide: The Kyosho Mini-Z Narrow GT Platform
MR-04 upgrade path from stock to competitive — what's different from the MR-03, what parts don't cross over, and what to buy first.
MR-04
The MR-04 EVO is Kyosho’s narrow-body GT platform — built for sports car shells that look cramped on the wider MR-03 chassis. The narrower track width and lower stance give it a more scale-accurate profile, and the shorter wheelbase options suit the body shapes it was designed for.
Deciding between platforms? The MR-03 vs MR-04 Buyer Guide covers cost, parts compatibility, and which is right for your track.
The upgrade path follows the same logic as the MR-03, but the platforms are not parts-compatible in every area. Confirm fitment before ordering anything.
Start Here: Bearings
Same as any Mini-Z — bearings before anything else. Stock plastic bushings create rolling resistance that no other mod can overcome. The MR-04 uses a set of 1150 (5×11×4mm) bearings similar to the MR-03, but verify the full set for your specific variant before buying a kit.
A full bearing replacement is the single highest return-on-investment mod on the platform.
FastEddy Sealed Bearing Kit for MR-04EVO2 (Amazon)
T-Plate and Rear Suspension
The MR-04 uses a T-plate based rear suspension, same concept as the MR-03. Carbon fiber replacements are the second upgrade after bearings.
The MR-04’s narrower track makes it somewhat more sensitive to T-plate stiffness than the MR-03. On high-grip RCP, a medium-stiff plate works well. On carpet or lower-grip surfaces, go softer to keep rear traction planted. Oversteer is more pronounced on the MR-04 at high speed — T-plate choice directly addresses this. See the T-Plate Setup guide for full flex selection and reading the car.
NexxSpeed Carbon Fiber T-Plate Medium (Amazon)
Tires
The MR-04 runs narrow tires sized for its track width — these are not the same as standard MR-03 tires. Compound selection matters the same way: match to your surface.
For RCP, 20–30° compound is the standard range. Softer compound grips more but wears faster. Start at the middle and adjust based on how the car rotates mid-corner.
Kyosho Mini-Z Low Height Slick Tire 30° MZW39-30 (Amazon)
Motor and Drive
The stock brushed motor is a starting point. Pinion gear changes are still the cheapest tuning lever — going smaller reduces top speed and increases punch out of corners, which suits the MR-04’s tight-turning nature.
Brushless conversion is available and worthwhile for competitive use, but the motor mount geometry differs from the MR-03. Use MR-04-specific brushless kits rather than adapting MR-03 parts. The Brushless Conversion guide covers motor sizing, ESC selection, and LiPo integration.
Hobbywing EZRUN Mini28 Combo — ESC + 3500KV Motor (Amazon)
Body Compatibility
The MR-04’s value is in the body shells it unlocks — narrow GT and sports car profiles (Ferrari F12, Lamborghini variants, Porsche 911 shapes) that look better on this chassis than the MR-03. Wheelbase options cover the common range for those shells.
When selecting a body, match the wheelbase and confirm narrow-body offset. Bodies listed as MR-03 compatible are often not dimensionally correct on the MR-04. The Body Compatibility guide has the full wheelbase and offset chart.