i wouldnt go that far. the newer T series are pretty baller.
the T3/T67DBB is an awesome turbo
the SC62 is nasty
GT turbos are great, but there are other alternatives, like the bullseye power S256/264
the BEP/BW S256 compares to a 3076R and makes great power on the 1.8t.
there is also a newer 50trim floating around with a DBB CHRA that spools and respools like a GT turbo, and makes more up top than a 3071R.
on my k03 setup i went chip, ebay downpipe and a catback. that was it. drove it around for a while and went GT.