Upgrading the K20C1 Turbocharger: Drop-in MHI Stage 2 vs Full Custom Turbo Kits
That moment when you’re pinned back in the seat of your Civic Type R, the tachometer sweeping past 6,000 RPM, and you realize the factory turbo just isn’t delivering enough up top—you’re ready for more, but the real question is how much more and at what cost.
If you’ve spent any time in the Honda tuning community, you know the K20C1 is special. It shares DNA with the legendary K-series engines that have powered everything from track monsters to daily drivers for decades . And here’s what’s wild: tuners are pushing this engine past 600 horsepower while keeping the internals completely stock . That’s double the factory output of 306 hp, and it’s changing what people think is possible from a four-cylinder Honda.
But not all turbo upgrades are created equal. The big decision facing Type R owners is whether to go with a drop-in MHI Stage 2 or commit to a full custom turbo kit. Let’s break down what each path looks like, what they cost, and most importantly, which one fits your goals.
TL;DR
The MHI Stage 2 turbo is a direct bolt-on from Honda’s OEM turbo supplier that supports 500+ horsepower with excellent spool characteristics and near-stock drivability. Full custom kits from brands like PRL, Spoon, and 27WON offer higher peak power (600-700+ hp) but require more supporting modifications and come with higher costs. For most Type R owners doing mixed street and track driving, the MHI Stage 2 hits the sweet spot of power, reliability, and affordability. For those chasing dyno numbers or building serious track cars, the custom route unlocks the K20C1’s full potential.
Key Takeaways
- The MHI Stage 2 is built by Honda’s OEM supplier—you get factory reliability with significantly more power
- Custom kits like Spoon, PRL P700, and 27WON Kuro deliver bigger numbers but need more supporting parts
- Ball bearing turbos offer better response and durability than journal bearing designs
- Fuel system upgrades are essential—the stock injectors can’t keep up with bigger turbos
- The K20C1 can handle serious power on stock internals, but there are limits
MHI Stage 2: The OEM-Plus Solution
Mitsubishi Heavy Industries makes the factory turbo on your Type R. That matters because when MHI releases a Stage 2 upgrade, you’re getting an OEM-quality unit that bolts on exactly like the stock one because the housings, mounting points, and footprint are identical .
The Stage 2 uses a 65mm 5+5 billet TD05-21HR3 compressor wheel (+7mm over stock) and a 52mm TD04-HLL1 inconel turbine (+5mm over stock) . That’s a significant step up in airflow capacity. The bigger compressor moves a lot more air so you make more boost and more power up top, and the larger inconel turbine handles the heat and drives that compressor without falling on its face .
Real-World Numbers
On pump gas, expect around 400 hp—that’s about a 33% bump . Step up to race fuel or ethanol, and the Stage 2 will support 500+ horsepower . The MHI Stage 2 was developed by Full-Race in partnership with Mitsubishi and Hondata, so the calibration support is solid .
Compatibility
The MHI Stage 2 fits FK8 (2017-2021), FL5 (2023+), Integra Type S, and can work with Accord 2.0T, RDX, and TLX with the FK8 downpipe .
The Spoon Sports Option
Spoon, the legendary Japanese Honda tuner, offers their own take on the MHI upgrade. Their big turbo kit uses the latest highly efficient MHI turbo with CFD-optimized compressor and turbine blades . The Spoon setup delivers 410 PS (about 404 hp) and 55.48 Kgm of torque compared to the stock 302 PS . They’ve increased the genuine 58mm compressor diameter to 65mm and modified the turbine from 47mm to 52mm, suppressing moment of inertia for improved response .
One critical detail from Spoon: “Since sufficient fuel supply is difficult to reach with normal fuel system, Hondata Fuel System install is required to provide the increased output” .
Custom Turbo Kits: Bigger Power, More Commitment
When you move beyond the MHI drop-in, you’re looking at a different class of turbo upgrades. Brands like PRL Motorsports, 27WON, and JSR Engines offer options that push the K20C1 to its limits.
PRL P700 Drop-In Turbo
The PRL P700 V2 is a 600+ horsepower capable drop-in turbo for K20C engines . It features a billet 304 stainless steel dual ceramic ball bearing CHRA for reduced weight and improved durability. The factory oil and coolant lines are retained, as is the bypass valve and wastegate actuator. PRL focused on efficiency with a taller compressor wheel featuring tapered tip exducer and cutback blade design for optimal spool and power .
27WON Kuro Turbo
27WON’s Kuro (Japanese for “black”) was designed from the ground up as a complete replacement with no core charge . Key features include:
- Point-milled 8+0 compressor wheel—more precise than flank-milled designs, nearly 12% lighter
- 9-blade Inconel turbine wheel for extreme temperature resistance
- TD04 ceramic ball bearing center housing for improved reliability over journal bearings
The 27WON unit runs a 50mm inducer and 67mm exducer compressor (compared to 49mm/58mm stock) and a 52mm/45.7mm turbine (stock is 46.5mm/41.25mm) . According to their testing, the Kuro outperforms other drop-in turbos across the entire RPM range, carrying 54 more whp at redline than the competition .
JSR MDR Ball Bearing Turbo
Built around Garrett’s G-Series CHRA platform, the JSR MDR features dual ceramic ball bearings and twin piston ring seals, handling exhaust temperatures up to 1922°F . Available in G25-660 and G25-700 configurations, both paired with a responsive .81 A/R turbine housing for fast spool and consistent boost delivery . These are genuine Garrett internals in a drop-in housing, offering Garrett-level reliability at a lower cost than a full frame kit.
Comparison Table: Drop-in MHI Stage 2 vs Custom Turbo Kits
| Turbo Option | Peak Power | Bearing Type | Compressor Wheel | Installation | Price Range |
|---|---|---|---|---|---|
| MHI Stage 2 | 500+ hp | Journal | 65mm billet | Direct bolt-on | ££ |
| Spoon Big Turbo | ~410 ps | Journal | 65mm billet | Bolt-on | ££ |
| 27WON Kuro | High 500s | Ceramic ball | 50/67mm billet | 100% bolt-on | ££ |
| PRL P700 V2 | 600+ hp | Dual ceramic ball | High-efficiency billet | Direct bolt-on | £££ |
| JSR MDR G25-700 | 700+ hp | Dual ceramic ball | 54/67mm Garrett | Bolt-on | £££ |
What It Takes to Support Big Power
Here’s the thing about turbo upgrades on the K20C1—you can’t just bolt on a bigger turbo and call it a day. The supporting modifications matter enormously.
Fuel System Upgrades
The Spoon kit explicitly requires the Hondata Fuel System (injectors, increased fuel capacity, and software) because the stock system can’t supply enough fuel for the increased output . For builds targeting 500+ hp, you’ll need upgraded injectors, a higher-flow fuel pump, and likely a flex fuel kit for ethanol tuning.
ECU Tuning
You absolutely need a tune for any turbo upgrade. Hondata and Ktuner are the standard options for K20C calibration . The MHI Stage 2 was developed in partnership with Hondata, so you can expect solid off-the-shelf calibration options.
Cooling and Airflow
A good intercooler upgrade is essential—the stock unit heat soaks quickly under sustained boost . You’ll also want a cold air intake, downpipe, and charge pipes to let the bigger turbo breathe. According to one builder’s recipe for 650 hp: “First is going to be a turbo upgrade. Second is going to be a cold air intake with a MAF conversion kit. Next is port injection and a flex fuel kit. After that is downpipes and charge pipes. Then an intercooler upgrade. And finally a tune” .
The K20C1’s Hidden Strength
The K20C1 is engineered with significant headroom. A recent build by German tuner Dragy pushed an FL5 Type R to 620 crank horsepower and 535 lb-ft of torque with the stock engine internals completely untouched . The hardware list included an MHI Stage 2 turbo, Eventuri intake, and Hondata cams, running 2.2 bar (32 psi) on E85 . The car ran 60-130 mph in 7.18 seconds at full street weight—genuine supercar territory for a front-drive hatchback .
However, there’s a nuance worth noting. According to 4 Piston Racing, who have extensive experience building K20C engines, “We’re bending rods at 400 horsepower, which is unlike Hondas in the past. This engine is a totally different approach” . So while some cars are making 600+ on stock internals, there’s debate about the long-term reliability ceiling. The engine has different weak points than earlier K-series motors, and not every build is created equal.
Drop-in vs Custom: Making the Choice
Choose MHI Stage 2 If:
- You want OEM reliability with proven power gains
- You’re aiming for 400-500 hp
- You want a straightforward install that retains factory components
- You value spool and drivability as much as peak numbers
Choose Custom Kit If:
- You’re chasing 600+ hp
- You’re building a dedicated track or drag car
- You want the latest technology (ball bearing CHRA, optimized aerodynamics)
- You’re prepared for higher costs and more supporting modifications
Frequently Asked Questions
What’s the difference between the MHI Stage 2 and Spoon Sports turbo?
Both are MHI-based upgrades using OEM-quality components. Spoon’s kit includes their specific tuning philosophy and achieves around 410 ps. The MHI Stage 2 is rated for 500+ hp and was developed with Full-Race and Hondata, offering a broader power ceiling. Both bolt on like stock.
Do I need a tune if I install a drop-in turbo?
Yes, absolutely. The ECU needs recalibration to properly fuel and time the engine with the increased airflow. The MHI Stage 2 was designed with Hondata tuning, so that’s a natural pairing. Running a bigger turbo without a tune is dangerous for the engine.
Will a bigger turbo ruin drivability?
That depends on the turbo. The MHI Stage 2 and Spoon units are designed to preserve low-end response while adding top-end power. Some larger custom turbos will lag more noticeably. The trade-off is peak power versus responsiveness. If you’re mostly street driving, stick with a setup that prioritizes spool.
Can the K20C1 handle 600 hp on stock internals?
Builds have proven it’s possible, though there’s debate about long-term reliability. Some engine builders note the K20C bends rods at 400 hp, while others have made 620+ on stock internals. A conservative approach with proper tuning and fueling is key.
What’s the cost difference between drop-in and custom?
Drop-in MHI units and Spoon turbos are typically more affordable and require fewer supporting modifications. Custom options with ball bearing CHRA and larger wheels cost more and demand a more extensive parts list. Factor in fuel system upgrades, tuning, and supporting hardware for the full picture.
Is the 27WON Kuro a drop-in or custom?
The 27WON Kuro is a 100% drop-in fitment turbo that bolts on exactly like the factory MHI unit . It’s a direct replacement with no core charge, but it uses more advanced internals (ceramic ball bearing CHRA, point-milled compressor wheel) than the standard MHI Stage 2. It bridges the gap between OEM-level fitment and custom-level technology.
Final Thoughts
The choice between an MHI Stage 2 and a full custom turbo kit comes down to your goals. The MHI Stage 2 represents the smart money for most owners—OEM reliability, serious power gains, and straightforward installation. It transforms the Type R from a 306 hp hot hatch into a genuine 500+ hp weapon while keeping the car usable and predictable.
For those chasing the absolute limits, the custom options from PRL, 27WON, and JSR deliver incredible potential. But they also demand more investment—not just in the turbo itself, but in fuel systems, cooling, tuning, and potentially engine internals. When you’re pushing past 600 hp, you’re in rarefied air where every component matters.
Here’s the truth about K20C1 turbo upgrades—you either go with the proven OEM-plus solution and enjoy a reliable monster, or you commit to the custom path and accept the complexity and cost that comes with chasing every last horsepower. Both are valid choices. The key is being honest about what you actually want from your Type R.
For further reading on Honda performance and turbo upgrades:
What’s your experience with K20C1 turbo upgrades? Running an MHI Stage 2 or something more custom? Drop your thoughts in the comments below.
