Don't waste your money. If the alternator or regulator are bad the car may not perform properly due to inadequate and/or fluctuating voltage which if serious enough will affect the engine management system. Same if there is a seriously defective primary connection. With either of these many of the accessories such as the stereo system may not work right either. The original poster's car may have had one of these problems. In either case properly repairing the defect will restore the full original performance. Beyond that the cabling and grounding designed in the car are more than adequate. The resistances in them are negligible.

To verify the condition of the charging and primary electrical system an accurate voltmeter is required.