the flapper on the 987 plenum actuates at different rpm than the resonance flapper on the manifold. if you search you can find a description of the activation points. also note when you look at the ecu pinouts that the signal for the plenum flapper comes from a different pin than the signal for the mainifold flapper, which would indicate that it's triggered at a different point.
otherwise, the boots that join the plenum to the manifold are rubber and have enough give to fit a larger plenum - no need for adaptors.
|