the argument is moot. The only options for a more real power for the E is to:
A: Turbo charge.
B: motor/trans/ECU swap.
Neither are cost effective for a daily driver based on a pre-existing perfectly running E. On either you would be forced to find some work around to met emissions inspection if your state requires this. As mentioned previously, the E is a very well built vehicle. The more you mess with it trying to "get a little more out of it" the chances of that reliability failing are put into question. This is why many add their opinions when asked about getting more power from the E. Its not a vehicle made for power, its a vehicle made to be put to use and to keep going.
Its already been shown by moding the existing air box negates an aftermarket unit and the cost of exhaust is offset by the price for whatever added power you may get on a daily driver vs the revs needed to access that power made by the aftermarket exhaust.
Other things like magnets on the fuel line, a blower fan inline with the air filter/intake, a resistor swap or any other "quick power fix" are all snake oil. If anyone can come up with a reasonably priced, reliable and proven power addition to the E, it would have been here already. Personally I hate to see people dump money into something that they either dont need or will not gain them their expected end result so I'll voice my opinion on it.
For power, I have a stock 69 Cougar Eliminator, another 69 Cougar with a 393 stroker and AOD trans and lastly a 65 Falcon with a late model roller motor and T5 trans thats built to the teeth and sounds like a speed boat. Id love to have that power and torque from the Falcon in the E but I dont see how its needed nor would I want to deal with the legalities of CA vehicle registration and smog certifications much less the cost involved. It goes back to being a moot point.
The E is what it is and it does that better than anything in its class. Thats why were here