OMFG, it's like a whole new, better car!
With audible feedback from the engine, I can finally drive it smoothly. It was almost dead silent before, so it was difficult to work smoothly between the throttle by wire and variable electronic boost. And then there is the turbo lag, which isn't really there anymore. It boosts right up to 21 PSI along with my right foot.
Now, the sound quality is what really blew me away. I was skeptical, because I just picked the cheapest stainless steel aftermarket exhaust for a Fiesta ST. It sounds straight up exotic. Cruising at 60 MPH, you might think it was a miniature Cummins idling along. Wind it up to the redline, and it is just more betterness. Not raspy, not droning, just a sweet baritone song. I love this car twice as much now.