I wouldn't put too much weight on your G-Tech results... I have one that says I'm putting out ~250HP but my timeslip says otherwise (~400HP). The G-Tech can be a useful tool to determine the relative effectiveness of various mods but I think the absolute power/tq reported can be quite inaccurate. As for advancing the cam, you will not increase your cylinder pressure without advancing the cam.... at the very least install it straight up (with ground in 5* advance) and see if that feels a little more stout. Are you sure you're getting good spark at the higher revs? How did you set your valve lash? How are your valve springs?

-Chris