duong,
No subwoofer level setting is "right" until you actually calibrate the level using a sound level meter and test tones (meaning, you need to buy a RadioShack meter if you don't have one yet). A receiver upgrade will NOT give you a better bass -- it is the issue of correct subwoofer calibrations. Also, subwoofer placement will have a HUGE effect on the quality (and quantity) of bass sound.
I would get the sub placement and calibration right first. That alone will likely let it beat your brother's system.
