IAG Performance IAG-ENG-1828 Stage 4 Extreme EJ25 Closed Deck Case Half Set w/Plugs (No Bore / Hone)

The Stage 4 Extreme is IAG's strongest and most prepared EJ25 Closed Deck offering. The case halves are split and the main webs are CNC machined in our Haas VF-4SS CNC mill for 9.5mm pins to reduce distortion and movement of the case in extreme conditions. The case halves are then reassembled and IAG machines the case to accept the IAG CLOSED Deck Inserts that transform the block into a solid deck. The unique inserts feature small passages that allow needed coolant flow to the deck surface. The case halves are then CNC machined for our new Fire-Lock head gasket solution that is loosely derived from diesel technology where a counterbore step is machined around each cylinder bore allowing specially sized fire rings to drop into the machined area and head gasket bores. The Stage 4 Extreme case is CNC drilled and tapped to fit 14mm head studs. Utilizing the new Fire-Lock gasket solution along with larger IAG / ARP 14mm head studs, nuts, and washers reduce the chances of the heads lifting under extreme boost conditions. Finally, ARP case bolts are installed and torqued before line honing the completed case in our in-house Sunnen CH-100 machine. IAG's Closed Deck is suitable for street or race use and has been tested in vehicles producing 1000+ horsepower and over 55psi of boost.

This Part Fits:

Year	Make	Model	Submodel	Notes
2002	Subaru	Impreza	WRX
2003	Subaru	Impreza	WRX
2004	Subaru	Impreza	WRX
2005	Subaru	Impreza	WRX
2006	Subaru	Impreza	WRX
2007	Subaru	Impreza	WRX
2008	Subaru	Impreza	WRX
2009	Subaru	Impreza	WRX
2010	Subaru	Impreza	WRX
2011	Subaru	Impreza	WRX
2012	Subaru	Impreza	WRX
2013	Subaru	Impreza	WRX
2014	Subaru	Impreza	WRX
2004	Subaru	Impreza	WRX STI
2005	Subaru	Impreza	WRX STI
2006	Subaru	Impreza	WRX STI
2007	Subaru	Impreza	WRX STI
2008	Subaru	Impreza	WRX STI
2009	Subaru	Impreza	WRX STI
2010	Subaru	Impreza	WRX STI
2011	Subaru	Impreza	WRX STI
2012	Subaru	Impreza	WRX STI
2013	Subaru	Impreza	WRX STI
2014	Subaru	Impreza	WRX STI
2005	Subaru	Legacy	GT
2006	Subaru	Legacy	GT
2007	Subaru	Legacy	GT
2008	Subaru	Legacy	GT
2015	Subaru	WRX STI
2016	Subaru	WRX STI
2017	Subaru	WRX STI
2018	Subaru	WRX STI
2019	Subaru	WRX STI
2020	Subaru	WRX STI
2021	Subaru	WRX STI