Supertech Inconel Exhaust Valves for Focus RS Select::Exhaust 31mm Sodium Filled (Set of 8) (FEVI 2502F HS 8) as they occur Bore Size Compression Ratio:(K625M86AP) 86mm (.04" 1mm Overbore) 8.6:1 as they occur The Driveshaft Shop 2 piece carbon fiber driveshaft for the Evo 7 8 9 uses a carbon fiber front and rear section with a specially designed hanger bearing and bracket that eliminates the violent hanger lag that occurs when power is put through the factory shaft *Sodium Filled* +1mm Oversize 31mm The Inconel 751 Nickel Base Alloy material is used for exhaust valves in engines that reach very high temperatures and its use is growing with the application of turbos and superchargers