HoLun:
Stock Y manifolds are dual plane. If you are thinking of opening the plenum under the carb, do NOT take out the front-to-back divider under the carb. I tried it years ago, created a mid to high speed miss on my supercharged Y. I welded a divider back in, cured the miss. You can open the plenum front to back on each side, like on the Blue Thunder, but again, do not take out the divider.
John in Selma, IN
John - "The Hoosier Hurricane"
