Cooling is very good, even with low noise low cfm fans like silencers or 80mm L1A panaflos. For more, use M1A panaflos, mid-range sunons or similar. For even more, high output 80mm sunons or similar would give wind tunnel-like results, just depends on how much noise you can stand.
The sx-Antec's low restriction design allows fan selection alone to determine airflow; no cutting, hacking or chopping is necessary.