This simple kit will do it all.  Heavy duty aluminum fittings are provided to vent your carburetors into the air box.  The fittings are designed to accept a "balance line" so each carburetor sees exactly the same pressure drop from the air box.  New vent and balance lines are part of each kit.  One way valves insure a steady one-way negative flow to the air box stabilizing float bowl pressure for accurate jetting across the power band.  This kit automatically synchronizes your carb jetting.