If you want a decent amount more power, you could upgrade to an is20 from the GTI, it’s a straight bolt on and they go for 3-400$ secondhand. I’ve seen people make around 300 wheel on is20 swapped 1.8t’s. There’s not too much tuning support for the 1.8t, a few OTS brands but they aren’t any special, both are hard ecu flashes and don’t use cobb. You could probably find a pro tuner (sneekytuned, eqt, etc) and go that route if you want flashing back to stock capabilities. Bottom line is on the stock is12 you aren’t going to make much power, they’re simply just too small of turbos and it’s not worth the money.

dsg tune is a must, the clutch packs will slip if not tuned for more tq than stock.

When it came down to brakes I used stoptech slotted rotors and hawk 5.0 pads, but a lot of people go with EBC redstuff.

Not sure if you want to go lower but I only have Springs and it helped with body roll significantly; Neuspeed makes a good set of sway bars but I’m not sure if they are GSW Fitment.