drift was mentioning that JG Engine Dynamics was working on a destroked version of the H22A. By using a shorter stroke, you lessen the high RPM loads on the crank, rods, rod bolts, wrist pin, and piston. It also increases the rod/stroke ratio which permits better airflow at those high RPMs. This combination, along with a lot of stronger parts and reworked head will allow you to run a much higher redline; I think that drift was talking about 9000 rpm. The good airflow will keep the torque up, and the hp will follow (remember that hp ~= torque * rpm ).
buh_buh is right though - doing this right will force you to replace nearly every moving component of the engine. A new, custom forged crank alone will probably ring upwards of $3k. My very uninformed guess is that this would be at least a $10-$12k engine.
Look into a turbo.