Hi,
i test custom build valves for my AAH engine (without turbo).
The design from valves is very important for good power. The old engine has bad valves, in addition to work on flowchannels and change cam it gives very good results. Better shape- more flow, less weight.
Build with a CNC machine and polished. Not the last possible things are do on my design, not reduced to minimum, but lifetime are good.
Look at the pictures!