as rweatherford said, you'll want to clean up your ground spot.
On the protege's the ground point is actually quite bad, It's only a 8 guage with very thick strands that connects the chasis to the negative terminal on the battery.
remember if you're running stereo equipment, you want your ground to be a lower guage that the positive wire you're running, for the maximum amount of power.
think of it as a hallway with a huge door on one end and a small door on the other, You'll get a bottle neck at the negative/ground wire or the small door.