moving timing belt 1 tooth foward or backward

Hey guys... I once read that moving the timing belt 1 tooth foward or backward would increase power vs better gas mileage.. Could you tell me which is which ?
My timing looks perfect... RPM~ 600-700 but my power is low.. Cyl. pressure is about 120psi in each.. other than that car runs OK... I just need a bit more power esp. at start-ups..
Thanks
My timing looks perfect... RPM~ 600-700 but my power is low.. Cyl. pressure is about 120psi in each.. other than that car runs OK... I just need a bit more power esp. at start-ups..
Thanks