When sourcing car audio capacitors, the most critical specification is the Farad rating (Capacitance); the industry standard is 1 Farad per 1,000 watts RMS of amplifier power. You must also verify the Working Voltage (typically 16V-20V DC) and the Surge Voltage (up to 24V) to ensure the unit can handle alternator spikes. Additionally, prioritize capacitors with Low ESR (Equivalent Series Resistance), as a lower ESR allows for faster energy discharge, which is essential for maintaining voltage stability during heavy bass hits.