I wonder what would be more effective, paying $99 for a 6" 350 CFM combo or buying two 4" 190 CFM combos for $94. I would assume two for less would do a better job but I wonder where the diminishing returns are.
Not sure but 190+190=380= greater air flow. but where are you venting to? would you need to make two holes?
would you want to deal with multiple controls though? seems to me like a bigger one would be a simpler solution?