Hey and welcome, nice to see another 1.8t owner.
Hw bads the 0-60 time ? you should be around 8 - 8.5 seconds. if its really bad disconnect your MAF sensor ( 1st connector after the airbox, will take a pic of the boras one think it uses the same just set out differently ) and see if that makes a difference.
This will make the car run on a standard map rather than an x dimensional one, as there is nothing to monitor the amount of air coming in at at what temperature.
The MAFs are pretty poor if the get even the slightest bit of dirt on them they will start to give lower readings to the ecu. you
can clean them with solvent (carb cleaner) although this doesn't always work best to replace then. Have a look on
VAGPARTS. dont go with the cheap things off ebay.
if disconnecting the MAF doesnt make a difference get it to a decent mechanic, who has an diagnostic scanner, to give it a scan for fault codes (Audi will charge you around £70 -100 for a scan alone, my local does it for £25 and i bought a copy of vagcom and a lead of ebay for a total of £65 now can scan it myself).