Remember the Holley 3 Barrel?

The 950 model had boosters on the secondary side. The 150 model only had "dump tubes" stickin outta the carburetor body that just dumped raw fuel right into the secondaries.

There was also a funky setup that made them a double pumper that consisted of a gear drive for the primary and secondaries, as well as a squirter that attached to the primary squirter screw that ran over the choke tower and dumped right into the secondary side.