Cosworth CNC Big Port Head Castings (07 STi)

Cosworth CNC ported cylinder heads feature dyno tested and flow bench proven ports, engineered for maximum usable power. Each new cylinder head is ported on a 5 axis machine to ensure consistency and perfect port shape every time. Additionally, larger intake (+1mm) and exhaust valves (+1mm) are utilized to help increase flow. Cosworth CNC ported Big Valve cylinder heads come complete with a performance valve job, hi rev (max 10,500rpm) valve springs with titanium retainers and are ready to install. Perfect for high performance applications.  20001699 is designed to fit 2007 WRX STI EJ25 (2.5L) North American spec vehicles or 2006-2007 Euro/Asia application using electronic throttle control. *Please contact Cosworth for futher details*

• CNC Ported/Machined finish port
• New Castings
• Hand blended finish work 
• Intake 13.63% (average) 19.38% (max) increased flow
• Exhaust 31.44%(average) 37.78% (max) increased flow
• 4-angle Inlet Valve job
• 3-angle & radius Exhaust Valve job
• Valves are lapped
• Back-Cut Inlet Valves
• Heads are Ultra Sonic cleaned prior to assembly
• Heads are Serialized and sport a machined Cosworth logo
• +1mm Stainless Steel Intake Valves (1800 degrees max.)
• +1mm Inconel Exhaust Valves (2400 degrees max.)
• Performance Valve Springs
• Titanium Retainers
• Hardened Steel Spring Platforms
• Knife edged ports