any fan can be any cfm ?? look up your fans specs .
you can have a fan that's 3000rpm and say 30 cfm or you can have one that's 3000rpm and 104 cfm . 0r one that's 1600 rpm at 30cfm or 1600 at 104 ??
it all in the blade design and housing like acting with a shroud affect what ever , the fan manufacture designs / engineers the fans to fit a speced need at any given rpm to produce any CFm rating
like I showed here
''the stock fan is 104 cfm@2000 rpm the replacement fan is 158 cfm @3000 rpm should be fine just about = same cfm per rpm [ .053 per 1 rpm .053 x 3000 = 159 0r .053 x 2000 = 106 ''rounded off '' .05266666.....]
so them 2 fans even not speced the same shows thy do the same work [cfm] pre rpm used so at...