Are you running your stereo without the car running? If so you probably want to get a capacitor. I've got a Ford Motorsport battery witout a capacitor. I have a 4 ga. power wire kit and a MTX Thunder250D amp, a two way MTX crossover network, three 10' MTX BlueThunders and I've had no problems.
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Crazy Contour Guy
www.geocities.com/contourcrazy