Kaptainkish

I recently upgraded my twin 502 MAG MPI powerplants. It was time as they were very near the 600 hr. mark and an oil analysis indicated some seawater in the oil and well above average wear. I had Tyler Crockett reprogram the ECU's and a local machine shop (Heartbeat racing) did the machine work and assembled the long blocks. Sounds and runs great so far, except that I keep blowing out brand new Mallory Marine (as well as now both of the OEM ones) ignition coils on the Port Motor. The longest one has lasted is about 1 hr of run time (that was an OEM coil) at speed. Anybody have experience with this? Is this most likely a ground issue? or?