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RSE Japan
FORGED PISTON SET EJ25 99.75mm CH30.70 (STD/2.6) CP
RSE CP Forged Piston Set for Subaru EJ25 – 99.75mm CH30.70 (STD/2.6)
🔧 Planning an EJ25 engine build?
The RSE EJ25 99.75mm CP Forged Piston Set, part number RA202A-SB02AP, features A2618 aluminium alloy construction, a 30.70mm compression height and a manufacturer-listed piston crown volume of −18.8cc.
The 99.75mm bore is 0.25mm larger than the manufacturer-listed standard bore. The 30.70mm compression height matches the manufacturer-listed standard specification.
This CP version carries the manufacturer’s “STD/2.6” designation. Confirm the intended crankshaft stroke and connecting rod configuration with your engine builder. Final displacement depends on the bore, crankshaft stroke and complete engine setup.
🚗 Listed Application
✅ Engine: Subaru EJ25
✅ Vehicles: Subaru GR/GV WRX
Confirm the actual engine variant fitted to your vehicle and its compatibility with this piston set. The listed vehicle application does not establish compatibility with every EJ25 engine configuration.
The 99.75mm oversize bore requires cylinder block assessment and appropriate machining before installation.
⚙️ Product Specifications
✅ Brand: RSE — Real Speed Engineering
✅ Manufacturer part number: RA202A-SB02AP
✅ Product type: Forged piston set — CP version
✅ Manufacturer category: Block Related / Piston
✅ Manufacturer configuration designation: STD/2.6
✅ Bore: 99.75mm — 0.25mm above the manufacturer-listed standard bore
✅ Material: A2618 aluminium alloy
✅ Compression height: 30.70mm — manufacturer-listed standard height
✅ Piston crown volume: −18.8cc
✅ Valve reliefs: Yes
✅ Piston pin diameter: 23.0mm
✅ Piston pin length: 63.5mm
✅ Circlip internal diameter: 23.0mm
✅ Listed piston weight: 390.0g
✅ Listed piston pin weight: 130.0g
✅ Combined piston and pin weight: 520.0g per piston and pin
📏 Manufacturer-Listed Ring Dimensions
✅ Top ring: 1.20 × 3.50mm
✅ Second ring: 1.20 × 4.00mm
✅ Oil ring: 2.00 × 2.70mm
Confirm the complete supplied component list and quantities before ordering. Use the specifications listed for RA202A-SB02AP when checking replacement pins and rings.
🛠️ Fitment & Installation
Professional cylinder block inspection, measurement, machining and engine assembly are required. Your engine builder should confirm the block’s suitability for a 99.75mm bore, piston-to-wall clearance, ring end gaps, deck clearance and piston-to-valve clearance.
Although valve reliefs are provided, piston-to-valve clearance must still be checked against the intended cylinder head, camshaft and valve timing configuration.
The listed piston crown volume is not a compression ratio. Final compression ratio must be determined from the complete engine configuration.
This product is a piston set, not a complete stroker kit. A 2.6L build requires a compatible crankshaft, connecting rods and other supporting components. Replacing the pistons alone does not establish that configuration.
📩 Need help with your build?
Contact KM Auto Group with your vehicle model, year, exact engine variant and planned crankshaft and connecting rod configuration for assistance with specifications, pricing and availability.
AUD $1,538
Available on backorder
Q1. What makes RSE exhaust systems high quality?
Please note: Q1 and Q2 below relate to RSE exhaust systems. This product is a forged piston set. Please refer to the product description and specifications for details of this set.
RSE (Real Speed Engineering) exhaust systems are designed and manufactured in Japan with a strong focus on quality, performance and precision engineering.
Developed with Japanese performance engineering expertise, RSE products feature:
✅ Premium full titanium construction on selected systems
✅ Lightweight, performance-focused design
✅ Precision TIG welding and high-quality craftsmanship
✅ Optimised exhaust flow and excellent fitment
✅ Distinctive exhaust sound and improved driving experience
✅ Motorsport-inspired engineeringRSE is associated with the same Japanese manufacturing group as TOMEI USA, combining Japanese engineering expertise with performance-focused product development.
Whether you are building a street car or a dedicated track car, RSE offers an excellent balance of quality, performance and value.
Q2. Are RSE exhaust systems suitable for daily driving?
Absolutely! Many RSE exhaust systems are suitable for daily-driven performance vehicles, depending on the model, configuration and local regulations.
RSE exhaust systems are designed to offer:
✅ Improved exhaust flow
✅ Significant weight reduction
✅ Potential improvements in throttle response
✅ Aggressive exhaust sound under acceleration
✅ Lightweight titanium construction on selected modelsMany RSE exhaust systems also include a removable silencer to help reduce exhaust noise when required. However, silencer availability varies by product.
Important: Exhaust sound levels and road legality vary between models. Please check your local state or territory’s roadworthy, noise and emissions requirements before purchasing or installing an aftermarket exhaust system.
Q3. What does "Available on Backorder" mean?
If this product is marked “Available on Backorder”, please contact KM Auto Group to confirm local stock and supplier availability before ordering.
Items not held in our local stock may need to be ordered from our supplier in Japan.
Before placing your order, please confirm:
✅ Current supplier availability
✅ Estimated dispatch time
✅ Estimated international shipping and delivery timeframe
✅ Engine configuration and product compatibility
✅ Supplied components and quantitiesSupplier dispatch estimates do not include the full delivery time to your address. Delivery times may vary due to order processing, international shipping and customs clearance.
Please review KM Auto Group’s applicable backorder and special-order terms before placing your order.
Contact our team for assistance with product specifications, fitment, pricing and availability.
