This is false, with DI there is a lot more control when fuel enters the combustion chamber vs port injection. Your knock sensors aren't going into overdrive running 87 octane on a stock tune.
Even on my roush tune on my F150 3.5 eco I can still run 87 without issue.
2015 F150 FX4 3.5 Eco with a 6.5' bed with the max tow package mods include:
Roush PP1 Package (Tune & Intake)
Ford Performance Sport Exhaust
Fox 2.0 Suspension
RTR Wheels w/ 305/65/18 BFG Ko2's
Updgraded Infotainment to Sync 3
Bushwacker Fender Flares
Future Plans starting this spring:
I have a PP1 with the x-springs. My plan down the road is to upgrade the dampeners to the FP version. I believe this will be an excellent combination for a street car that will see the track occasionally.
Wife said I could either go through with this project or do an overlanding setup on my F150 (rack, rooftop tent etc). I'm more interested in overlanding, so I'll be doing a trans and diff fluid change and calling it good.