The AFM probably doesn't help, but I have a feeling the stock 8v cam is a bit mild, as is the compression ratio. But then you're probably talking maybe 20hp tops when that is upgraded along with some good headers and no cat, and the fuel/ignition re-tuned to take full advantage of. You may be able to get 30 hp with a ridiculous cam, solid lifters and lots of bottom end work to make high power delivery at rpm in excess of 7000 possible. It could be done but would be major $$$$ for a relatively small gain. One reason why I hold alot of respect for the Honda B18 type R motors. They pretty much come that hot out of the "box", only they're making 180 hp out of 1.8L.
Even the standard B18 is nothing to sneeze at, and can be bumped up with some $$$.