I installed mine as well, removing only the the part of the intake track that they recommend in their online PDF (two screws into the front grill, then a couple push tabs to remove the "U" portion from the grill feed into the air box. It was pretty tight and I don't have huge hands.
I have it set on "Race" for a 4.0 PSI boost. I don't see much of a reason to set it lower, its a relatively small gain and well within stock turbo limits.
The boost gauge in the app is pretty horrible - I wasn't expecting much more, but it doesn't seem to maintain a good connection. Otherwise, the app works well enough to change maps.
I don't get a lot of chances to go WOT, or really to get on it that much. I'm often in traffic or have my boys in the car with me, which is why I never bothered with a full tune. From a roll, it's really hard for me to notice much of a difference in any gear. Just a few minutes ago, I started from a dig at a stop sign on the way into work and spun right through first and second, and it pulled pretty damn hard in 3rd - that was the first time that I could confidently say that there is a little more power. The tire spin is due to having 5 year old Blizzaks on lol - not because its some build monster of a GTI now.
I give it an overall rating of "meh".
For the price, if I notice it occasionally...cool.
Also - mine never asked for a MAC address like it says it would? Says it is connected though...should I be concerned?