the 3 barrel Weber setups are individual throttle body setups as are the MFI setups, RSR used a variation called 'high butterfly' MFI. These all utilize a separate butterfly for each cylinder, street setups all have low butterflies that are efficient at separating the pressure waves from the pistons of one cylinder from interfering w/ the adjacent cylinders
Current thinking is to use low mounted ITBs as used on the Webers and MFI setups w/ a plenum and electronic control via Motec or similar EFI controls.
Single throttle body setups w/ or w/o a plenum are subject to intake manifold pressure fluctuations from cam timing events where the pressure waves from one cylinder interfere w/ adjacent cylinders and have become common on modern smog motors which and to use very mild cams which minimize intake manifold pressure fluctuations.
MFI manifolds w/ low butterflies
964 w/ single TB and plenum
TWM 46mm aftermarket ITBs, low butterflies
964 3.8RSR w/ low butterflies and plenum
low butterfly ITB 964 w/ GT3 plenum
