OE (Original Equipment) Valve Springs The valve springs that were originally fitted to the XE engines are amoungst the components that were changed for the later production engines. In both cases they are single valve springs but the later type springs (i.e. engine number 14142839 onwards) are an improvement.
Race Springs Even though the later type OE springs are an improvement on the earlier valve springs they are still not suitable for race applications. For all of our mechanical cam profiles we highly recommending upgrading to our race spings, which are included as standard in our more advanced upgrade kits.