There is nothing obstructing the holes at all. When I take a hit I hold the battery itself and not the tank. I see threads through the holes. Is there some sort of seal that is keeping me from drawing air or something?
Take the tank off the batery and suck on it to see how the airflow is.
Is there a "CE" sticker covering one of your airholes? I just checked on of my evod tanks and noticed that they happened to put a sticker on the base and it was covering 1 of the two airholes.
unless you prefer a draw on the tight side, i'd drill the holes out BIG. like 2mm or 1/16 inch.
the air has to pass through the center pin on the atomizer head itself, and then pass thought the slot on the end of the atomizer:
coil head showing airhole at bottom of coil head and the slot that the air has to flow through sideways.
also, if there is eliquid all over the ego threads, I guess that could obstruct the airflow.