"Tuner" for a V-10

OK..... There seems to be some misconceptions about tuners. First, when there are any changes to the ECU, it is logged with time, date, and ID code. This stays in the ECU until it it wiped, which means it is a completely blank. Ford put many blind allies in their programs to prevent hacking, and changing the program. Tuner companies put quite a bit of time going down the rabbit hole, to reach success. The changes to the fuel trim and timing curve must stay within some set parameters to prevent engine damage, and a long life. Some of the changes are in sample rates. I don't know what the factory sample rates were, but increasing the rate allows the engine to respond quicker. Fords full throttle, was not really Full Throttle, to keep emissions down and pressures in the engine, remember, the recommended oil was 5-20W, they are now moving toward 5-30W. After a few years of the tuners working wonders with Fords engines, they seemed to see the light, so to say, and allowed tuners to have access the the code bases, to improve engine performance and economy, while keeping within the emission standards. The catch was Ford could have access the these programs for their factory vehicles, and save the time and money that would be required to develop their own programs.
If any manufacture claims that an aftermarket part causes the failure, they must prove it in court. Granted, they will drag it out as long as legally possible. Cylinder pressures are influenced by a number of parameters other than compression ratio. Valve lift and timing, air fuel ratio, heat, and load are the main ones. Our Lincoln has a 2.0 L with a 12:1 ratio and guess what the owners manual says to use for fuel, good quality regulator unleaded.
If you contact the tuner with your VIN, and ask them if you will see any benefit from their tune, they are usually truthful, and will tell you the truth.