do performance valves make a noticeable difference in power or are they mainly just for durability?

 

it depends if they are just identical parts (in a diff material) or if they are oversize.

Typically they dont give any performance advantages.

 

**Ferrea** ...the valves we use special aerospace quality alloys, including EV8-Z18, which provides high tensile strength. An exclusive two-step slow forging process ensures proper grain flow and virtually eliminated any damage to the material structure. The valves are then heat treated and stress-relieved over a 48-hour period, which is the crucial base of our molecular integrity. These valves feature avionics-quality hard chrome along with a specially applied hard tip. Our engineering staff at Ferrea spends countless hours conducting flow bench tests to achieve an optimum balance of flow, velocity and efficiency in the design of this valve. As a result, these valves incorporate smoother radiuses and unique undercuts. These exclusive features are what make the Ferrea Competition Plus Valves unequaled in performance and reliability ***

Do you think the unique undercuts make any noticeable power gains? I'm buying these for the durability and to reduced friction in the valvetrain.

I'd like lightweight hollow stem valves. if anyone knows a company that makes them for the D16Y8... let me know.