Latest addition to the ProX program is the Steel Intake and Exhaust Valve & Spring Kits. This kit is offered as an alternative where the OEM application uses Titanium valves. ProX has now developed the Steel Intake and Exhaust Valve & 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 OEM valves & valve springs and can be installed using the OEM retainers bases and valve seals.