The Acura RSX, produced from 2002 to 2006, is a front-wheel-drive sports compact that has earned legendary status among Honda enthusiasts. Its lightweight chassis, double-wishbone suspension, and available K20A2 or K20Z1 engines make it a prime candidate for performance upgrades. Whether you're aiming for a daily driver with a bit more punch or a full track build, choosing the right aftermarket parts is critical. In this comprehensive guide, we cover the best brands for Acura RSX performance parts — from intake systems and exhausts to cams and engine management — with a focus on proven brands like K&N, Injen, Skunk2, and several others that can transform your RSX’s capabilities.

K&N Performance Parts

K&N Engineering has been a trusted name in automotive filtration for decades. Their products are designed to increase airflow while maintaining excellent filtration, making them a go‑to for RSX owners seeking a simple, reliable horsepower gain. K&N’s washable and reusable air filters also reduce long‑term maintenance costs.

K&N Air Filters

The direct replacement drop‑in air filter for the Acura RSX (part #33‑2031‑2) is a high‑flow cotton gauze element. It fits inside the stock airbox and can increase horsepower by 1–3 hp on a otherwise stock engine. More importantly, it improves throttle response and filtration efficiency over the factory paper filter. K&N says these filters can last up to 50,000 miles between cleanings with proper care.

K&N Cold Air Intakes

For more significant gains, K&N offers a cold air intake system (part #69‑1020TR) for the RSX. This system replaces the restrictive factory intake tube and airbox with a mandrel‑bent aluminum tube and a large cylindrical filter located outside the engine bay. By drawing in cooler, denser air, the RSX can gain an estimated 5–8 hp at the wheels. Installation is straightforward with basic hand tools, and the kit includes all necessary hardware.

K&N Oil Filters

While not a direct power adder, K&N’s premium oil filters provide superior flow and filtration, helping protect your engine during high‑RPM driving. The high‑efficiency media and silicone anti‑drain back valve make them ideal for RSX owners who track their cars or run synthetic oil.

Injen Performance Parts

Injen Technology is known for its innovative intake and exhaust designs that maximize airflow and produce a distinctive sound. Their parts are engineered specifically for each vehicle platform, ensuring a precise fit and real world performance gains.

Injen Cold Air Intakes

Injen’s SP Series (Super Performance) intake for the RSX (part #SP1091P) is one of the most popular aftermarket intakes. It features a polished aluminum tube and a large cone filter with a heat shield. Dyno testing by Injen shows gains of 8–10 hp and 6–8 lb‑ft of torque. The filter is washable and the MR (Moisture Resistant) design prevents filter degradation even in wet conditions. Injen also offers a “Race” version with a shorter tube for better mid‑range response.

Injen Exhaust Systems

For the RSX, Injen manufactures both cat‑back and axle‑back exhaust systems using 2.25‑inch or 2.5‑inch mandrel‑bent stainless steel tubing. Their SES series (Super Exhaust System) features a straight‑through muffler design that reduces backpressure while providing a deep, aggressive tone without being excessively loud on the highway. Expect gains of 4–7 hp and a weight reduction of 5–8 pounds compared to the factory exhaust.

Injen Intercoolers and Charge Pipes

For RSX owners with forced induction kits (turbo or supercharger), Injen offers high‑flow intercoolers and aluminum charge pipes. These components reduce intake air temperatures and improve flow, helping to prevent knock and allowing more timing advance. They are often paired with Injen’s intake systems for a complete air path upgrade.

Skunk2 Performance Parts

Skunk2 Racing specializes in high‑performance engine components for Honda/Acura K‑series engines. Their parts are developed for serious street and race applications, with a focus on camshafts, intake manifolds, and valvetrain components that unlock substantial horsepower.

Skunk2 Camshafts

Skunk2 offers several camshaft profiles for the K20A2 and K20Z1 engines in the RSX. The Stage 1 camshafts are a direct drop‑in that provide a mild power gain (5–10 hp) with a smooth idle. Stage 2 cams (such as the “Pro 2” series) offer more aggressive lift and duration, yielding 15–25 hp gains, but require upgraded valve springs and retainers to prevent valve float. Stage 3 cams are best for full race builds with high compression pistons and aftermarket ECU tuning. Skunk2’s camshafts are made from billet steel and case‑hardened for durability.

Skunk2 Intake Manifolds

The Skunk2 Ultra Series intake manifold is a popular upgrade for the RSX. It features larger plenum volume, shorter runners, and a 70mm throttle body opening. This design improves airflow across the entire rpm range, with particular gains in the mid‑range and top end. Many users report gains of 8–12 hp with proper tuning. The manifold is also compatible with OE sensors and comes with a billet aluminum fuel rail.

Skunk2 Valve Springs and Retainers

When installing aftermarket camshafts, upgrading valve springs is essential to prevent valve float at high rpm. Skunk2’s dual valve spring kit provides enough seat pressure for aggressive cam profiles up to 9,000 rpm. The titanium retainers reduce reciprocating mass, allowing quicker revs and higher reliability.

Skunk2 Headers

Skunk2’s stainless steel headers for the RSX feature 4‑2‑1 or 4‑1 designs with large collectors and mandrel‑bent primary tubes. They are designed to scavenge exhaust gases efficiently, granting 5–8 hp gains on a naturally aspirated setup. The headers are available in both ceramic coated and polished finishes to resist heat soak and corrosion.

Other Top Brands for Acura RSX Performance

Beyond K&N, Injen, and Skunk2, the RSX community relies on several other manufacturers known for quality, fitment, and real gains. Here are the most notable.

AEM Air Intake Systems

AEM (Advanced Engine Management) is a longtime rival of K&N and Injen. Their dry flow air filters do not require oiling, eliminating the risk of sensor contamination. AEM’s cold air intake for the RSX (part #21‑408) uses a multi‑pleated synthetic filter and a sealed aluminum tube. They claim gains of up to 10 hp. AEM also offers water‑injection kits and engine management systems for the RSX.

Greddy / Trust – Turbo Kits

Greddy is famous for its bolt‑on turbo kits. The Greddy T518Z turbo kit for the RSX (Discontinued, but still available used) provides a reliable 250–300 whp with proper tuning. Modern kits from Greddy and associated brands like GReddy Performance Products include intercoolers, wastegates, and blow‑off valves. For those seeking FI (forced induction), Greddy remains a favorite.

Hondata – ECU Tuning

Hondata is the gold standard for tuning the K‑series ECU. Their FlashPro system allows you to upload custom calibrations via a laptop, adjust fuel and ignition maps, set rev limits, and enable launch control. For RSX owners who install intakes, exhausts, cams, or forced induction, a Hondata FlashPro is almost mandatory to fully utilize the parts and maintain reliability. The FlashPro also allows datalogging and real‑time monitoring.

PRL Motorsports

PRL Motorsports is a relatively newer brand that has gained a strong following for its high‑quality silicone intake pipes, cold air intakes, and intercooler kits. Their “Racing” intake for the RSX uses a large 4‑inch filter and 3‑inch tubing, offering gains similar to the top brands but with a focus on maximum flow. PRL also produces charge pipes for turbo conversions and high‑volume fuel rails.

Hasport – Motor Mounts

When increasing power, engine movement becomes a problem. Hasport offers polyurethane motor mounts that reduce wheel hop and improve throttle response. Their RSX mounts come in various durometers (62A, 62A with billet aluminum inserts) to balance comfort and performance. These mounts are essential for any RSX making over 200 whp.

BC Racing – Coilovers

While not a power part, suspension upgrades are critical for putting power down. BC Racing coilovers are popular among RSX owners for their adjustable damping and ride height. Their inverted monotube design provides excellent handling for street and track use. BC Racing also offers camber plates for the RSX, allowing proper alignment after lowering.

How to Choose the Right Performance Parts for Your RSX

With so many options, selecting the best parts for your Acura RSX depends on your specific goals, budget, and mechanical skill. Below are key considerations.

Define Your Power Goal

Are you after a mild daily‑driver upgrade (15–30 hp) or a high‑output build (200+ whp)? For modest gains, a cold air intake from K&N or Injen plus a cat‑back exhaust from Skunk2 or Injen will suffice. For 30–50 hp, add camshafts and a Hondata reflash. For more than 200 whp, you will need forced induction (turbo or supercharger) with full fuel system upgrades, a stronger clutch, and extensive engine management.

Compatibility and Model Years

All RSX models (Base, Type‑S, and 2005‑2006 revisions) share the same chassis and suspension, but engine variations exist. The 2002–2004 Type‑S uses a K20A2 with 200 hp, while the 2005–2006 Type‑S has a K20Z1 with 210 hp. Some intake and exhaust parts are interchangeable between years, but check manufacturer fitment guides – especially for cams and headers, which may differ in valve timing and exhaust port shape.

Budget and Tuning Requirements

Many bolt‑on parts require ECU tuning to get full benefit. For example, a cold air intake may run without tune, but a larger throttle body or camshafts will cause a check engine light and poor drivability without a custom calibration. Budget at least $500–600 for a Hondata FlashPro plus tuning time. Also consider that aggressive cams may require upgrading valve springs and retainers (adding $300–$500).

Installation Skill Level

Swapping an air filter is a 5‑minute job. Installing a cold air intake or cat‑back exhaust is a weekend project for a DIYer. Camshaft installation, however, requires timing belt/chain removal, special tools, and careful assembly. Turbo kits require fabrication and welding in some cases. Be realistic about your abilities or budget for professional installation.

Installation and Tuning Considerations

No matter which brands you choose, proper installation and calibration are essential for reliable performance. Here are some specific tips for the Acura RSX.

Intake Installation

Cold air intakes place the filter in the front bumper area, which is susceptible to water ingestion during heavy rain. Use a hydro‑shield or bypass valve if you drive in wet conditions. Also ensure the filter is well secured and not rubbing against the radiator or frame. Many intakes require removal of the front bumper or wheel well liner for access.

Exhaust Upgrades

When replacing the exhaust on an RSX, be aware that removing the factory cat can cause emissions test failures. If you use a test pipe or high‑flow cat, the ECU may require a secondary oxygen sensor spacer or a tune to eliminate a check engine light. Skunk2 and Injen exhaust systems come with all necessary gaskets and hardware; reuse the factory hangars if possible.

Engine Management Tuning

Hondata FlashPro is the most user‑friendly option for RSX tuning. You can start with a basemap from Hondata or a professional tuner, then adjust on the dyno. For forced induction setups, a wideband oxygen sensor is strongly recommended. Do not attempt to run a turbo without proper fueling and ignition control – K‑series engines are robust but will detonate under lean conditions.

Supporting Mods

If you increase horsepower significantly, consider upgrading the clutch (e.g., Exedy Stage 1 or Stage 2), lightweight flywheel (e.g., Fidanza), and fuel pump (e.g., Walbro 255 lph). The stock RSX clutch slips easily above 230 whp.

Final Thoughts

The Acura RSX remains an incredibly rewarding platform to modify, thanks to a vast aftermarket community and the tunable K‑series engine. Brands like K&N, Injen, Skunk2, AEM, Greddy, and Hondata offer time‑tested products that deliver measurable gains. Whether you choose a simple air filter upgrade or a full forced induction build, always prioritize quality parts, proper installation, and professional tuning. With the right selection, your RSX can become a thrilling, reliable performance car that stands out at any meet or track day.

For more details on specific part numbers and dyno charts, visit the official websites of K&N, Injen, Skunk2, Hondata, and PRL Motorsports. Community forums like ClubRSX.com and K20a.org also offer extensive owner experiences and tuning guides.