yes, I currently have about $70 pads up front and cheaper ones in the rear, and I have drilled rotors, standard size, but drilled on all four corners. It just seems with that amount of weight.... i need an upgrade to a dual piston caliper up front or something

 

An extra 400 lbs of sound system in the trunk is no big deal; unless you're always riding around with a full load of people inside the car, you're still well within the car's design specs (ie figure 175 lbs per person per available seat, plus a trunk full of luggage is what the car is designed for anyways). If you think that you need more stopping power- thats no big deal, you can always upgrade- but the stock brakes are just fine for that.


The number of pistons is really irrelevant- dual piston calipers typically have smaller pistons, so your total piston area is usually about the same- its just that the pad is clamped more evenly (among other things).

The easiest ways to substantially increase braking power for our cars are by increasing the coefficient of friction of the brake pads (buy a more performance oriented set)- or to increase the size of your rotor (places the force from the caliper further from the axis of rotation, increasing your total torque; like moving your hand out further on a wrench).