Paul,

On the RWS web site this page showing your intake castings
(http://www.rotaryaviation.com/intake_manifold1.htm) is
posted.  Do you have one piece castings for a PPort
design?

I am starting with a 89-92, series 5, FI, non-turbo. motor
with the goal of getting ~300 Hp at 9000 rpm for use in a
BD4c or RV10.

Thank you;

JD Grubbs

You will need over 3:1 in your gear box to get 300 HP at 9,000 RPM
Most props bottom out at 2700 RPM.