What size line does the vac booster need from the manifold?

[motzingg]

pretty simple question... looks like the hose that was on my booster was 1/2" maybe? seems like over kill, i'd like to run a 3/8" hard line to clean up the install. Would that cause problems?

[HIO Silver]

A hard line would be fine but it'll need a section of hose to take up the engine's vibration. The hose should also be reinforced against collapsing due to the applied vacuum.