really? ive only seen these pushed to stage 3 with 280hp... stage 3 chip, turbo back exhaust, open air intake only way i see to make more HP than that, would be to throw in a larger turbo, but then you have to find a way to custom tune it and also to bypass the computer to allow it to make more boost....it would not be easy AT ALL if i was going that far to do it, ide get a larger bottom end out of a cobalt, some nice forged internals, port/polish my head, slap it on there with some cams, and a gt35r.... run a stand alone ecu and bypass all the factory shit....but then youre left with a very raw car, killing all resale value, making the SID worthless, etc...it can be done, but its definately not easy to mod these if youre looking for much more than 280bhp....and cant forget, EXPENSIVE as hell to mod