The latest addition to the ProX program is the Exhaust Valve and Spring Kits. This kit is offered as an alternative where the O.E.M. application uses titanium valves. ProX has now developed the Exhaust Valve and Spring Kits, containing a set of steel intake or exhaust valves plus a set of specially designed stronger valve springs. The ProX kit just replaces the O.E.M. valves and valve springs and can be installed using the O.E.M. retainers, bases and valve seals. Steel valves for increased durability and less wear under extreme conditions. Nitrided valves offer high micro-hardness while super-smooth surface finish reduces friction between stem and guide. Special stronger valve springs deal with the extra weight of the steel valves. Springs are made from premium chrome vanadium steel for higher performance and durability at high RPMs.