Has anyone ever noticed a difference between JDM 1st egn B16A valves and USDM B16A valves in the area of the tip and or keeper groove? I had got a set of Ferrea valves in for my B16A head and noticed they where quite different at the tip and keeper groove then the stockers I pulled out. The keeper groove sat much lower on the stem. I called Ferrea and they said that the reason I am seeing the difference is because JDM valves are different then the USDM which they use as the spec for the valves they sell. Has anyone run into this and what kind of problems did they have with installed height if any?