The Subaru WRX and STI have earned legendary status in the performance car world. Whether you own a classic EJ-powered bugeye or a modern FA-equipped VA or VB chassis, the right modifications can transform your driving experience. At American Fusion Wheels in Shawnee, KS, we help WRX and STI owners across the Kansas City metro build their dream cars — from bolt-on basics to full Stage 3 builds.
Here is our guide to the best exhaust, wheel, and intake mods for your Subaru WRX or STI.
Top Exhaust Brands for the WRX and STI
An aftermarket exhaust is one of the most popular first mods for any WRX owner. It unlocks sound, reduces backpressure, and sets the stage for bigger power gains down the road. These are the brands we recommend and install most often:
- Invidia — The N1 and Q300 cat-backs are staples in the Subaru community. The N1 delivers an aggressive rumble, while the Q300 keeps things refined with a deeper, quieter tone. Both are constructed from SUS304 stainless steel for long-term durability.
- Tomei — The Expreme Ti is a titanium single-exit exhaust that shaves serious weight and produces one of the most iconic exhaust notes in the game. It is loud, lightweight, and race-inspired.
- GrimmSpeed — Known for precision-engineered downpipes and cat-back systems that pair perfectly with their intake and intercooler products for a complete power package.
- AWE Tuning — Their Track and Touring editions give you a choice between all-out performance sound and a civilized daily-driver tone, both with exceptional build quality.
Ready to upgrade your exhaust? Check out our Subaru exhaust installation services for professional fitting and tuning support.
Best Wheel Brands for the WRX and STI
Wheels are where performance meets style. Dropping unsprung weight with quality forged or flow-formed wheels improves acceleration, braking, and handling. The most popular fitments for the WRX are 18x9.5 +38 and 18x9.5 +45, while STI owners often run 18x10 +40. Here are the top brands:
- Enkei — The RPF1 is arguably the most popular aftermarket wheel in the Subaru world. It is lightweight, strong, and available in multiple finishes. The NT03+M is another excellent choice for a more aggressive look.
- Rays — As the manufacturer behind Volk Racing and Gram Lights, Rays produces some of the finest forged wheels available. The TE37 is a motorsport icon that looks right at home on any WRX.
- Volk Racing — The ZE40 and TE37 Saga lines represent the pinnacle of forged wheel technology. They are expensive, but the weight savings and strength are unmatched.
- Work Wheels — Japanese craftsmanship at its best. The Emotion and Meister lines offer both one-piece and multi-piece options for those who want a truly custom setup.
- Option Lab — A budget-friendly flow-formed option that punches well above its price point. The R716 is a popular choice for daily-driven WRX builds that still see occasional track days.
We carry and install all of these brands. Visit our Subaru WRX customization page to see what we can do for your build.
Intake and Intercooler Upgrades
Once you have exhaust and wheels sorted, the intake and intercooler are the next logical steps toward real power gains. These components feed your turbo cleaner, cooler air for consistent performance:
- Cobb Tuning — The SF Intake system is designed to work seamlessly with Cobb's Accessport and off-the-shelf maps. It is the go-to choice for owners who want reliable, tune-supported power gains without guesswork.
- PRL Motorsports — Their intake and intercooler kits are engineered for maximum airflow. The front-mount intercooler upgrade is especially popular on FA20 WRX builds where heat soak is a common issue.
- GrimmSpeed — The top-mount intercooler kit for the STI and their front-mount kit for the WRX are both excellent. Paired with a GrimmSpeed intake and exhaust, you get a fully integrated bolt-on package.
EJ vs FA Engine: What It Means for Modding
Understanding your engine platform is critical before choosing parts:
EJ25 (2002–2021 STI, 2002–2014 WRX)
The EJ is the classic boxer engine that defined the STI. It responds well to bolt-on mods but is known for ringland failures under high boost without proper tuning. Equal-length headers eliminate the signature rumble but improve power, while unequal-length headers preserve that classic boxer sound. The EJ has decades of aftermarket support, making parts readily available.
FA20/FA24 (2015+ WRX, 2022+ WRX with FA24)
The FA platform uses direct injection and a twin-scroll turbo, making it more efficient and responsive out of the box. It handles bolt-on modifications well and is less prone to the reliability issues that plague the EJ at high power levels. However, it requires an electronic boost controller or Accessport for proper tuning after modifications. The FA24 in the 2022+ VB chassis makes more torque and responds even better to intake and exhaust upgrades.
Stage 1, 2, and 3 Build Paths
We help WRX and STI owners build their cars in logical stages:
Stage 1 — Bolt-On Basics (10–30 WHP gain)
Accessport with an off-the-shelf or custom tune, intake upgrade, and a recirculating bypass valve. This is the foundation every modified WRX should start with.
Stage 2 — Exhaust and Intercooler (30–60 WHP gain)
Add a downpipe (catted for street, catless for track), cat-back exhaust, front-mount or upgraded top-mount intercooler, and a professional protune. This is the sweet spot for most daily-driven builds.
Stage 3 — Turbo and Internals (100+ WHP gain)
A bigger turbo, fuel system upgrades (injectors, fuel pump, flex fuel kit), forged internals, and a custom dyno tune. Stage 3 builds require professional installation and tuning — this is not bolt-on territory.
Explore our full range of sports car modification services to plan your build.
Why Professional Installation Matters
Modern Subarus are precision-engineered machines. Improper installation of exhaust components can cause boost leaks, check engine lights, and even engine damage. Wheel fitment mistakes lead to rubbing, premature tire wear, and compromised handling. Intake and intercooler installations that are not properly sealed create boost leaks that rob power and can cause lean conditions.
At American Fusion Wheels, our technicians have hands-on experience with WRX and STI platforms. We ensure every bolt is torqued to spec, every clamp is sealed, and every modification works together as a system. We also work with local tuners to make sure your car runs right after every upgrade.
Ready to start your WRX build? Call us at 913-291-2027 or visit our shop at 12310 W 62nd Ter, Shawnee, KS 66216. We serve WRX and STI owners across Kansas City, Overland Park, Olathe, Lenexa, and the entire metro area.
