When I turbo charged by '86 Fox body we used upgraded ignition to fire a spark though a more densely packed charge. The N/A guys wanted (and still want) a hotter spark for a better burn. These days we turbo guys are re-gapping our plugs for a colder spark to avoid cooking our plugs. With this in mind, what's the upside of a more powerful coil if we're asking less of it as we dial-up boost?
Directly from Stratified (
http://stratifiedauto.com/blog/spark-plug-tech/): "For the Ford Ecoboost we still recommend a plug that is one step colder than OEM for mildy bolted cars especially since 21+psi of boost is quite common. For highly modified cars that see a lot of heat it is advisable to try a plug which is two steps colder than OEM."
I beat on my FiST - it's a track day car: I drive to the track, pound on it for 3 20 minute sessions, and drive it home. I certainly prefer OEM reliability over an aftermarket coil that is capable of producing a hotter spark that I won't ever use.
That said, there's no gains to be found with exhaust upgrades, either, but they sound and look cool, so that's on my list. I can't hear more powerful coils.
@TyphoonFiST: you're soooo close to having a giant killer! Forget about upgraded coils and get a tubular manifold for the GTX!