Originally Posted by TheRevJosh
Keep us updated on how the one the one step hotter NGKs work out for you over the next few weeks. After seeing the condition of my plugs after changing the stockers to NGK LTR6IX-11s and doing more research on spark plugs, I put a set of LTR5IX-11s in my Amazon cart. I was waiting until I have some more time to pull the trigger on them, but if they keep working for you I'll have to make some time.
You'll be fine with no appreciable loads on the engine, except you will eventually get cylinder temps high enough for the ECU to respond. It's the same problem, with the added risk of pre-ignition.
Remember the Ecoboost motors are marketed as being able to run on REGULAR 87 octane fuels.