Do you know about the new 3000CFM Spal?
Same form-factor as the 2300cfm 16" fan, but 3000CFM capacity.
Assuming you're using the 16" puller, this is a direct replacement and flows a ton more.
http://www.the-fan-man.com/shop/prod...roducts_id/216
If you're building a shroud, you might want to build it to fit that monster.
Byron