The problem I see with the proposed centrifugal fan is that while it may be able to provide the necessary cfm (per manufacturers website), it can't provide any pressure increase.
Look at the plot from the manufacturer. Its max pressure output is 1.2 inH2O (inches of water) at 0 CFM. That translates into a whopping 0.0433 psi at no load airflow. At max flow (262 CFM), it would be able to provide the air volume, but only at atmospheric pressure (0 psi boost). So it really wouldn't do much of anything that your airbox isn't already doing.
Looking at the electric supercharger page, you'll see that they give an example under their product desciption page saying that their unit provides the air at about a 0.5 psi pressure boost. That's how they can claim to increase horsepower. But still, it seems like a relatively low amount of boost that the solution could really provide, especially for $300. I'd just as soon use the money on the stock exhaust and probably see better gains throughout!
That's my take on it.
