The 2.5 liter block makes a great upgrade for all WRX models, since there is no replacement for displacement. The US STi block features a semi-closed deck for increased strength. This motor is physically a bolt-in for all US-market WRX and STi models (WRX's will require ECU tuning, bigger injectors, etc.)
1. THIS IS NOT A COMPLETE MOTOR: This is a fully assembled bottom end, which consists of a block, crank, rods and pistons only. You will need to reuse your stock cylinder heads or purchase replacements.
2. The OEM 2.0L WRX heads will bolt-on for to the 06/2006 & before 2.5L short block, but there will be a bump in compression.
3. For high-powered applications, we recommend replacing the cast OEM pistons in this block with CP Forged OEM-size units.