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IAG Stage 1 Plus EJ25 Subaru Short Block (WRX, STI, LGT, FXT)


  • $ 3,199.99
  • Save $ 16000

The IAG Stage 1 Plus short block starts with new Subaru 2.5L EJ25 engine case halves that are bored and honed to 99.75mm. IAG‘s in house honing process is able to set piston to wall clearances tighter for a quieter running engine. The short block is measured and assembled using a new 2012+ Subaru 2.5L heat-treated STI crankshaft that is matched to ACL Race or King main bearings. Early style OEM STI rods are utilized along with ACL or King rod bearings. The case halves are sealed with new OEM case bolts and sealant. Finally Manley 99.75mm Platinum Series Forged Pistons are spec'd and installed finishing off the short block.

The IAG Stage 1 Plus Short Block has a power output rating of 475BHP.

*All IAG Short Blocks are balanced and blueprinted.

Compression Ratio: 8.5:1 on D Cylinder Heads (EJ255)
Compression Ratio: 8.2:1 on B, V and W EJ257 Heads with standard thickness gasket.


  • Manley 99.75mm Platinum Series Pistons, Ringset, Tool Steel Pins and Clips (w/ Coated Skirts and Offset Wrist Pin)
  • New FHI Subaru Case Halves at 99.75mm
  • New FHI Subaru Early STI (Stronger Style) Connecting Rods
  • New FHI Subaru Heat Treated 2017+ STI Crankshaft
  • ACL or King Rod Bearings
  • ACL or King Main Bearings
  • New FHI Main Case Bolts
  • IAG Spec Blueprint Sheet
  • Power Output Rating: 475BHP

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