Subaru EJ257 STI 2.5 Liter Short Block CASE 2002-12 WRX / 2004-12 STI

The addition of support ribs at the top and bottom of each cylinder substantially improves block rigidity and reduces cylinder distortion under severe conditions. The result is lower frictional losses (higher power output all other things being equal) and improved reliability over the standard open deck block. This block exhibits better cooling characteristics when compared to the closed deck type and is a better choice in all but the most extreme applications.

Will bolt up to WRX heads, however compression ratios will be altered.