Ya, Ford didn't screwup in the power department with the Ecoboost 2.3, 2.7 and 3.5. A local tuner here just posted a dyno graph of a 2.7 Ecoboost that put down 375/505 on a 93 tune. I don't recall if it had a downpipe but even if it did, that's pretty impressive.
I feel you though, other than my DD every vehicle purchase I make again will be based on the availability of aftermarket FI options.
Get silly toruque with a 3.5 and a e85 blend tune. 5.0 sounds nice and has overall more potenial but at <$1000 in mods the Eco wins.... sorry to say. Didn't want the the money pit of the mod path like my car. Love a 5.0 VMP or Whipple truck but overkill for my use.