Review on Inboard Ignition Coil Replacement for MerCruiser Thunderbolt IV and V Ignition Systems with HEI - Replacing 18-5438, 392-805570A2, 392-7803A4, 392-805570A1, 72115, 40511 by Patrick Diaz

I bought this aftermarket to install while my heavy duty hand made coil distributor is being manufactured and shipped. It took me ten minutes to install. Wow what a difference. I immediately heard and felt a deeper and stronger rumble while idling on my indoor Malibu ski boat. My problems with procrastination have been resolved. Also, it took several long holds to get it working in front of this new coil. Now it lights up immediately. Love it. I will still use my expensive heavy duty coil but would recommend this coil to anyone looking for it