Complete Guide to the Discover Japan Restrictor Plate Collec

[ashenweaver]

If you are trying to finish every upgrade requirement in the Discover Japan Collection Journal in Forza Horizon 6, the Restrictor Plate challenge is probably one of the first confusing roadblocks you will run into.

Unlike normal engine parts, the Restrictor Plate upgrade does not appear on most standard street cars. A lot of players spend time browsing upgrade menus wondering if their game is bugged or if they missed a hidden unlock somewhere. Fortunately, the solution is actually pretty simple once you know which cars and engine swaps activate the option.

Here is the easiest way to complete the Restrictor Plate upgrade and move one step closer to finishing all 47 Discover Japan upgrades.

Why the Restrictor Plate Upgrade Is Hard to Find

The main issue is that Restrictor Plates only appear on certain racing engines or specialized motorsport builds. If you open the upgrade menu on a normal production car, the category simply will not exist.

That means you need either:

A racing engine swap
A dedicated race car
Certain Time Attack-style vehicles

Once the correct engine is installed, the Restrictor Plate option becomes visible inside the engine upgrades menu.

Method 1: The Budget Miata Setup

Most players are using the classic Mazda MX-5 Miata because it is cheap, easy to modify, and can help complete multiple journal upgrades at the same time.

This is currently the fastest and most cost-effective method.

Step 1: Buy the Miata

Head to the Autoshow and purchase the NA-generation Mazda MX-5 Miata.

The car usually costs around 14,000 credits, making it one of the cheapest upgrade platforms in the game.

Step 2: Open the Upgrade Garage

Go into:

Custom Upgrades
Conversion Menu

This is where the important engine swaps are located.

Step 3: Install a Compatible Racing Engine

You need an engine that supports motorsport-style tuning.

The two commonly used swaps are:

Inline-Four Turbo Rally Engine
2.0L R3 Racing Rotary Engine

After installing either swap, return to the engine upgrades section.

Step 4: Install the Restrictor Plate

Now the Restrictor Plate category should finally appear.

Purchase and equip it, and the Discover Japan journal objective should complete immediately.

That is all you need to do.

Method 2: RX-7 Racing Engine Swap

If you do not want to use the Miata, another reliable option is the Mazda RX-7.

This method is a little more expensive but works just as well.

RX-7 Setup Steps
Buy or enter your RX-7
Open the Conversion menu
Install the 4-Rotor Racing Engine
Return to Engine Upgrades
Install the Restrictor Plate

The racing rotary setup automatically unlocks the restrictor upgrade path.

A lot of rotary fans actually prefer this method because the RX-7 can also be used for several other Discover Japan tuning objectives.

Method 3: Use Specialized Time Attack Cars

Some dedicated Time Attack vehicles and racing trucks already include Restrictor Plate support by default.

These are usually:

Prize vehicles
Motorsport reward cars
D-class Time Attack builds

If you already own one, check the engine upgrade menu before spending money on swaps.

Sometimes the Restrictor Plate category is available immediately.

Helpful Tips for Finishing the Full Collection Journal

The Restrictor Plate is only one part of the bigger Discover Japan upgrade checklist. If you are planning to clear all 47 upgrades, a few extra tricks can save a lot of time and credits.

Watch Out for AWD Swap Issues

If you convert the Miata to AWD too early, some stock clutch upgrades disappear from the menu.

The fix is simple:

Revert temporarily to the stock drivetrain
Purchase the clutch upgrade
Reinstall AWD afterward

A lot of players miss this and think their journal progress is glitched.

Rotary Compression Is Not Required

One common misconception is that the Rotary Compression upgrade must be completed for 100% journal progress.

Thankfully, it is not mandatory.

That upgrade only appears on select Mazda rotary platforms and can safely be ignored if your goal is simply completing the Discover Japan collection.

Fast Credit Farming Methods

Upgrade costs add up quickly when trying to unlock every tuning category.

If you start running low on credits, the best early-game money sources are:

Yellow Story Missions
Tokyo City Food Delivery jobs
Skill chain farming in dense city areas
Long drift routes around mountain roads

These activities also help raise your campaign level while funding your upgrade checklist progress.