its at least 1 5/8". thats the smallest they get for SBC. the super comps are thicker so thats good, but if they are either 1-5/8 or 1-3/4 they are probly bottlenecking caussing excessive heat, not to mention robbing horsepower.with that big of a blower i think you need alot bigger primaries.
im no engine guru, but i know a thing or two. i'd say you need at least a 1 7/8". maybe even a set of BBC headers w/ adapters, tho i dont know how well they work. you can get BBC headers off the shelf w/ 2"+ primaries.
wheres all the engine tech guys?