Hi all. I'm looking into replacing the valve guides in my B16a head. Its track only and apart for a refresh, so now is the best time to do so. I have a couple of questions regarding the guides.... 1. Has anyone got any suggestions about which to go for ? My options appear to be OEM Honda, aftermarket Ferrea or Supertech. If anyone has any feedback on any of those I'd like to hear it. Opinions backed up with actual experience would be great. 2. As the engine is used only on track and is in high cam revs most of its life, would there be any benefit in putting a taper on the guides to aid airflow ? Its something we can do and on paper it should help a little, but has anyone done it before ? I should point out the head will have a port, polish, 3 angle cut, and deshroud. I already have all the valve train to support any modifications. Thanks !