i use 4 inch CPU fans for intake. theyre rated anywhere form 70, 100 cfm. i you use one of these, your intake inlet can be just as big or smaller that your exhaust (dosent have to be 2-3x as big like with a passive intake.) you can find pre wired ones at buyextras.com and they cost about $20

you want to exhaust more air than you bring in to create a littel negative air pressure. this way, the stink stays inside.:rastasmoke: