The Maradyne EF8908 11" Champion Series fan is another great fan to use in a dual fan setup, with a strong puller rating of 1110 CFM / 1886 M3/H.
Maradyne Champion Series fans ship in a puller configuration, but they feature reversible blades so the fan can be converted to a pusher setup if space or practicality dictates. (When installed as a puller, the Champion Series fans more often than not produce a higher CFM than their SPAL counterparts.)
Check out the Maradyne EF8908 / M113K 11"Champion Series fan (featuring some new in-house product pics) here.