I don't have an answer for you, but thinking about it, what do coil packs do?
to the best of my knowledge, they are what create the power to make a spark at the tip of the spark plug, and if they don't make enough power, there will be a weak spark or no spark at all. If they make enough power, there will be enough spark to run efficiently. If they have more than enough power, there will be excess spark, and therefore extra heat to start the combustion process, which can make the gas combust faster, or maybe more efficiently than before.
So I could see them helping some, but i haven't heard of many people replacing them unless they are broken, and I would recommend the same. 15 hp seems to be a lot, and if the engineers at Ford figured that what you have now would last a couple hundred thousand miles without damaging anything, I would tend to agree with them. I would worry about the rest of the system being able to handle the extra power needed to run the "better" coil packs, if they draw more power, or create more power, then some wires will need to be upgraded to handle it, if not, they could, emphasis on could, heat up excessivly and burn themselves out.
Those are my thoughts and advice, but like I said, I've not heard much about upgraded coil packs so I could be completely wrong...
I hope that helps, but dont make any decisions based on what I say
