Annular primaries but regular secondaries. With the Edelbrock AVS2 models they build them with secondary venturis which the AVS do not have.
Edelbrock also has their new VRS 4150 series modular carbs. These also have annular boosters. The carb is also 1/2" taller giving a longer venturi length which may also contribute to better fuel atomization and thus vapourization. Sizes in 650, 750, 850 and 950 CFM ratings.
