On a stock engine I do not think you can get more power just by changing the air flow meter. It might help reduce restriction if you remove the mesh upstream of the sensing element (I do not know if your car has it). Problem is, you'll start to get all sorts of crud encrusted on your sensors wire.
As far as increase in power is concerned, maybe it enriches the air fuel mixture a bit.
If you're interested, I'll e-mail you a couple of articles that appeared in Autospeed Magazine (Australia) about Mass flow meter and air intake mods.
Question to Mods: Any possibility to upload small Pdfs?