"It'll be more daily driveable too."

Nothing wrong with its daily drivable performance at stock.

A stock Ex to a stock Si is about 30 or so hp diffrence along with a small amount of weight. Si averages around high 15's to low 16's in the quarter and the Ex is mid to high 17's. I don't feel the diffrence between these 2 cars. This is why I say a supercharger on a stock Ex is a waste of money if you ask me unless it was on a bigger engine.

I do like chimchim's advice, If you aren't flooring it or reving it really high then your not using the full potential of the stock engine.