I have seen people on here cut out the center of the manifold and match the opening with the weber adaptor. there is a ring on the primary side that is supposed to help with emissions, but it is not really needed. I plan to cut it out of Geronimo's manifold when I do the 2.0 head swap with the Mikuni Muscle cam. I have extra manifolds I can mod - may even bypass the coolant floor heater to help cool the intake. That mod requires the bottom of the manifold to be cut off, and the coolant passage plugged or rerouted under the whole manifold with a pipe like the heater return line on the right side of the block.