Going to the switched side of the master solenoid is the best place for + power, the battery absorbs and stabilizes power surges also. The 3? should be sufficient, 6? is the best, however not always possible. There is always some EMI in the main power feed from the EI coil divers as they charge and discharge. A 25 ?26kuf cap filter would still be beneficial, and also clean up any other EMI in the electrical system.
Thomas S.
www.G3ignition.com