I also read vibration of a loose pencil coil can cause premature failure so perhaps make sure any replacement coils are torqued up correctly 
I also wonder if the Trophy coils have a more positive engagement on the spark plug also ???? But certainly with 2 bolts holding them in position, rather than one on the stock coils, the Trophy ones are NOT going to vibrate.
Martin

I also wonder if the Trophy coils have a more positive engagement on the spark plug also ???? But certainly with 2 bolts holding them in position, rather than one on the stock coils, the Trophy ones are NOT going to vibrate.
Martin