How It's going

I've been getting my bearings for tuning since January this year and I'm nearly happy with it now.
does anyone know how much E85 percent you can run at higher power output (like 500 ish) before injectors run out? as far as i can tell, fhe turbos are the physical limit on 14.08 gases, and with 40% Ethanol it makes just shy of 480 wheel (CALCULATED NOT DYNOED) I use basic kinematics to calculate hp and verify with the 10ish lbs of air per min to 100hp rule.

I'm running 12.5 AFR, with a nominal commanded AFR of 17.5 until pedal of .49 when fuel enrichment hits. i can get seriously 26 mpg at 75mph with zero wind or hill. but I'm running 40% ethanol and the rest is 89 octane pump. it loves the mix and with around 14 deg of spark adv at 5500 in optimum power, it really picks up from stock. it's smooth, the trans shifts exactly how i want, but i Really want that every-time 520 ish (1hp:10lbs ratio) it is just not capable it seems of doing that. it says fuel limit, but it's clearly not running into a physical limit as the highest I've seen injector DC go is 32% and it'll say limit at commanded fuel pressure, and 16% injector DC and 46% HPFP DC. it's NOT low press fuel pump, I've got a 489 Pump that is wayy more than i need. it's not injector, even with simple math i can prove that. it's code. I've messed with calculated airmasses but does the truck use that if the MAP sensor is where the truck reads from?
the truck feels like constant HP after 4000rpm. i still think it's a turbo limit but it's hitting .831 wastegate DC and only 225k rpm. i know that's faster than stock but 2015's have billet comp wheels and my turbos are fine after 10k miles (yes, i inspected them with manifold install) I'm going to turn the wastegate preloae nuts a turn and see if i get more airflow but that should not really make a difference as the exhaust map is still 150 inhg, and turbos work off of exhaust velocity not pressure

BTW BD diesel manifolds are by far the best aftermarket part for the F150 3.5 outstanding quality and gets rid of annoying faulty factory parts. bonus for them is they spool the turbos quicker. not sure if the increase in exhaust flow helps since the turbo is THE restriction that bogs the whole system

On direct injected engines, fuel limits are more than just the physical amount the injector can spray.
There's only so big of a window in the engine cycle that the injector can spray during, usually a window of about 220 crank degrees.
You can open the window quite a bit, but eventually you'll hit it again and the only other options would be bigger injectors, a higher capacity HPFP, or aux injection (port injectors).

You sound like you're on the right track for sure, but also asking a lot of that setup.

As mentioned above you can open the injection window up *a bit* to avoid the insufficient fuel flow error, but another thing to watch is desired/actual HPFP psi. Remember the HPFP works on RPM and if you are demanding too much fuel too soon in the RPM range the actual will fall well below desired. One more thing to keep in mind is demanding more pressure won't necessarily help, as the VE of the pump (flow) goes down as pressure goes up. Running any amount of Ethanol blend will of course place more demand on the entire fuel system.