Wiseco K598M995AP Forged 99.50 mm Dish Pistons for Subaru EJ25 / EJ257 (9.0:1) For Sale

- AUTHORIZED DEALER
- AUTHENTICPART

Part Brand: Wiseco

Part Number: K598M995AP

• 2006–2007 Subaru Impreza WRX (EJ255 2.5L Turbo)
• 2008–2014 Subaru Impreza WRX (EJ255 2.5L Turbo)
• 2004–2007 Subaru Impreza WRX STI (EJ257 2.5L Turbo)
• 2008–2014 Subaru Impreza WRX STI (EJ257 2.5L Turbo)
• 2015–2021 Subaru WRX STI (EJ257 2.5L Turbo)
• 2004–2008 Subaru Forester XT (EJ255 2.5L Turbo)
• 2009–2013 Subaru Forester XT (EJ255 2.5L Turbo)

• Fits EJ255 and EJ257 turbocharged engines only
• 99.5mm bore is stock bore size; no overbore required
• Yields ~8.9:1 compression with 51cc cylinder head
• Piston-to-valve clearance must be verified during assembly
• Recommended piston-to-wall clearance: 0.003" (street) / 0.004" (race)

• Forged 2618 aluminum alloy for high-boost and nitrous applications
• Armor Plating on ring grooves and wrist pin bore for durability
• ArmorGlide skirt coating reduces friction and noise
• -19cc dish with four valve reliefs for oversized valves and high-lift cams
• Offset wrist pins reduce piston slap and friction
• Complex skirt profile optimizes ring seal and bore stability
• Crown design promotes cross-flow scavenging during overlap
• Designed to resist detonation and 99.5mm (3.917 in.) -- Stock size
• Stroke: 3.110 in. (79mm)
• Rod Length: 5.137 in. (130.5mm)
• Compression Height: 1.209 in. (30.7mm)
• Dish Volume: -19cc
• Wrist Pin Diameter: 0.905 in. (23mm)
• Wrist Pin Style: Press-fit or full-floating
• Top Ring: 1.25mm steel, gas nitrided
• Second Ring: 1.5mm cast iron, phosphate coated (Napier style)
• Oil Ring: 2.0mm chrome-plated carbon steel
• Piston Weight: ~371 grams
• Quantity: Set of 4

• 4x Forged pistons with Armor Plating and ArmorGlide coating
• 4x Steel nitrided/Napier ring sets (1.25mm / 1.5mm / 2.0mm)
• 4x Wrist pins (0.905" diameter)
• 8x Wrist pin retainer clips (Spirolox)

The Wiseco K598M995AP Sport Compact Piston Kit delivers race-proven strength for high-performance EJ25 turbo builds in the Subaru WRX, WRX STI, and Forester XT. Forged in-house from 2618 aluminum alloy using Wiseco's advanced grain-flow technology, these pistons provide superior strength for high-boost, nitrous, and aggressive street/track applications where cast or hypereutectic pistons fail. The -19cc dished crown with four generous valve pockets accommodates oversized valves and high-lift camshafts while the squish area design resists detonation and pre-ignition for extended engine life.

Current production pistons feature Wiseco's Armor Plating--an abrasion-resistant coating on ring grooves and wrist pin bores that increases aluminum hardness, prevents ring micro-welding, reduces carbon buildup, and combats detonation-induced corrosion. The ArmorGlide skirt coating further reduces friction for improved power output and quieter operation. Complete with premium steel nitrided top rings, Napier-style second rings, and chrome oil rings, this drop-in kit requires no overbore at the stock 99.5mm bore size. Offset wrist pins minimize piston rock and friction losses while the precision-machined ring grooves ensure optimal seal to minimize blow-by and oil consumption.

*Parts are for USA spec vehicles, please contact us to verify fitment on JDM & international models.

· · · SHIPPING · · ·

• Free shipping across the contiguous 48 United States (excludes Hawaii and Alaska). Item(s) ships on the same day or within 1 business day. Delivery time is within 2 to 4 business days excluding next day deliveries. Orders over $750 require signature for delivery.
• Canada customers - If does not collect import & duty fees during checkout, the shipping carrier will collect them prior to delivery.

· · · RETURNS · · ·

• Your complete shopping satisfaction is our #1 priority. If an item you ordered from us does not meet your expectations, please contact us within 30 days of receiving the item(s). If your order arrives damaged from shipping please contact us and we will provide a prepaid return label to send back for a replacement or refund.

• Returned items must be in the original packaging (including plastic wrapped items) and in brand new condition.
• Any returns received installed, mounted, used or missing components will be subject to return fee's.

· · · PAYMENTS · · ·

• We accept all payment methods through 's payment system
• PayPal, and all major credit cards/debit cards are accepted.

· · · response · · ·

• Customer satisfaction is a top priority for us. If you have any issues with your order, please let us know. We will make every effort to resolve any problems and ensure you are satisfied.

· · · CONTACT US · · ·

• We appreciate your business. If you have any questions, please message us through and we will respond within 24 hours on weekdays. Feel free to browse our store for other available items. Thank you again for choosing to shop with us!