The plastic on the TB get worn done (where the black plastic dics meets the metal leaver) If your getting low throttle readings via VCDS you need to clean and adapt ecu then dremil the metal off the upper opening stop on the TB, keep grinding bits off until the reading stops going up. It should end up around 84-87% on a few I have managed 89%.
I will try and make a quick iphone video tomorrow, its better then me trying to put it in words which I am crap at...lol
The main load/boost request maps are based on this throttle % reading, I bet there are 1000s of AGUs out there with less the 80% opening and the map not running its full power.