First to clarify I said similar mods. I had a 67mm on my car. I used the FP black as a reference in size. And a stock frame fp black is just to say hey I fit this into this.
Secondly
Most dont have to drop 10 k to reach goals. I can honestly say regardless of what we do in the USA in europe where this car will be the biggest deal is where the R&D will shine.
To get 500 rwhp out of a base 5.0 right now is more than a couple grand as well. Blower, exhaust, maybe cams and a tune. Still talking 6 or 7 grand.. and lets talk safely reaching those numbers.
I think we are under estimating the potential of the aftermarket crowd surrounding this platform. Remember its world wide now..
Ya it will have a big aftermarket but unfortunately it seems like it will go the way of all the other ecoboost engines. Where the majority of people modding them never get past bolt ons or modified stock turbo's. A few people will rig stuff up to pass what most do I just see that ford isn't really setting up a mod friendly engine. I could be wrong but going off the details already given i'd be surprised if over 400 crank hp was doable cheaply.
As far as building the motor and adding some kind of secondary auxiliary fuel system that can easily top 10k not to mention all the required airflow upgrades pre/post both sides of the compressor. You can get into GT + blower price range very quickly.