Easy Way to Finish the Restrictor Plate Upgrade Challenge in Forza Horizon 6

[PhantomGlide]

The Restrictor Plate Upgrade challenge in the Discovery Journal sounds more complicated than it really is. A lot of players waste time searching through upgrade menus without realizing that the restrictor plate option only appears on certain engine setups. Once you know which cars work, the challenge becomes a quick two-minute job.

After testing a few methods, there are several easy routes that consistently work. Some are cheap beginner-friendly options, while others are better if you already own higher-end cars or special editions of the game.

The Cheapest and Fastest Method

The easiest solution for most players is the Miata setup.

Buy the AX 5 Miata from the Autoshow for around 14,000 credits. It is cheap, easy to find, and works immediately once the correct engine swap is installed.

Here is the process:

Buy the AX 5 Miata.
Drive to any Festival Site or Player House.
Open Upgrades & Tuning.
Select Custom Upgrade.
Go to the Conversions tab.
Install the 1.6L I4 Turbo Rally engine.
Return to the Engine Upgrades section.
Open the Restrictor Plate option.
Install it, remove it, or simply toggle the setting.

As soon as the restrictor plate menu is changed, the challenge should complete instantly.

This is probably the best route for new players because the total cost stays relatively low compared to some of the other engine swaps in the game.

The RX-7 Method

If you already own the Mazda RX-7 Type R, this method also works very well.

The trick here is using the 2.6L 4-Rotor Racing Engine swap. Once installed, the restrictor plate option becomes available inside the Engine Upgrades menu.

This route is slightly more expensive than the Miata method, but many players already have an RX-7 in their garage, making it a convenient option.

The steps are almost identical:

Open Custom Upgrade

Go to Conversions

Install the 2.6L 4-Rotor Racing Engine

Return to Engine Upgrades

Toggle the Restrictor Plate option

That is enough to finish the journal requirement.

The Barn Find Route

Players who unlocked the Honda HSX-R GT Barn Find can also use that car for the challenge.

Equip the 1.6L I4 Turbo Rally engine swap, then head directly into the Engine Upgrades section. The restrictor plate category should appear automatically.

This method is nice because it uses a free Barn Find vehicle instead of requiring an Autoshow purchase.

Premium Edition Shortcut

There is also an extremely easy shortcut for Premium Edition owners.

The small Time Attack Truck found in D Class already behaves like a built race vehicle, so the restrictor plate settings are unlocked on the stock engine without requiring complicated swaps.

That means you can:

Open upgrades

Enter Engine Upgrades

Toggle Restrictor Plate

Complete the challenge immediately

No engine swap required.

Why the Challenge Confuses Players

The biggest issue is that the restrictor plate option does not appear on normal street engines. Many players open the Engine Upgrades tab on random cars and assume the feature is bugged or missing.

In reality, the game only unlocks restrictor plates on specific racing-oriented engine configurations. Once you install the correct swap, the menu suddenly appears.

That is why the challenge feels inconsistent until you know the exact cars that work.

Best Recommendation

For most players, the Miata route is still the best overall choice.

It is:

Cheap
Quick
Easy to reproduce
Available early in the game

You can usually finish the entire challenge in less than five minutes, even if you are starting from scratch.

If you already own an RX-7 or the Barn Find Honda, those methods are equally reliable. Premium Edition players have the easiest time of all thanks to the Time Attack Truck shortcut.

Once the restrictor plate is toggled, the Discovery Journal objective should complete instantly, letting you move on to the next upgrade challenge without wasting more credits experimenting with random cars.