I rarely post much on RCG's anymore so I'll respond here.
Good combo's for 480MiniFan:
1) Mega 16EDF (16/17/2) and 4s3300-4000's
2) Mega 16/20/2 and 4s 3300-4000's
The 16/20/2 is a bit heavier so will stand more abuse.
This calc program is invaluable:
http://www.s4a.ch/eflight/fancalc_e.htm
Get your motor constants off the Mega website if they are not listed on the dropdown menu.
-Mike