Finally somewhere I can chime in! I fit the Gearhead intercooler into my 13 MKS and just picked it up today.
Long story short, another driver hit me. Insurance covered whole front clip, gearhead intercooler released about that time. Collision shop slapped it in for free because they already had the crash bar off. Shitty situation turned around 360
Decided on a clear bra and ceramic coating... so i had to sit for over a month with the intercooler installed and couldn't test it (to let the paint cure).
Have a Livernois tune, and my butt dyno is very happy. Unfortunately because it was such a long wait, I'm full of "this is wild to drive" joy and dont have any quantitative comparisons yet. Turbo whistle is louder sooner, but haven't been anywhere near heat soak conditions.
I have an SCT from a friend who no longer has his car that I'm looking for a way to unmarry, but planning to put a GearHead tune optimized for the intercooler soon.
Was laying down 12.9s in SE MI last September, I should have a test and tune day coming up in the next month or so...
-B