We recommend that our EVO 8 and EVO 9 customers to upgrade their valves. These factory designed valves are not a good idea to use when doing engine related upgrades, we like to install a full set of stainless steel valves for strength and reliability. The factory valves can cause serious damage if you happen to break a timing belt or even over rev the engine as this can cause the valves to hit the pistons, at which time the valve stems will snap in two - not bend but snap off and then those big metal parts go every place into the chambers, the pistons, the cylinder walls, every where- causing very expensive damage that could have been prevented.
C Jackson:dsm: