piggybacking off of this post, it really does depend on how much you wanna spend.
a mate has the older 2.0tfsi (bwa) and did a k04 conversion (turbo, hpfp, intercooler, decat etc) and is pushing around 350bhp. the thing is a weapon but he paid a lot to get there.
so yeah, the potential is...
have a read of that thread, its in russian so translate the page using google translate.
the car is an a5, but the symptoms are the same, and the fan used on the a5 is the exact same part as on the a3's climate unit.
part number is 8P0959101, so...
1. your car doesnt have a maf, it has a map sensor. item 2 in photo
2. part number is 1k0129684ae. the piece thats broken is part of the larger air intake pipe. around £42 from audi new. easy to change, just a few spring clips.
short answer: either, theyre basically the same.
288mm and 312mm pads are the same, but there seem to be a very slight (by slight, i mean literally a mm difference in width) between available 312mm pads.
1ZE=288mm. oem pad pn 5K0698151
1LJ=312mm. oem pad pn 5K0698151...