I have a 1998 1.8T with an AGU engine. It as remapped at RTech nearly 40,000 miles ago. Lots of torque now, if peaks at higher torque figures than a standard TT with the 225 BAM engine and so it pulls well by the time you get to 2.5K revs. BHP only went up to 183 from the original 150. I still enjoy driving the car after owning it for 18 years as you can feel it pull much better.
So get it to somewhere like RTech who will check it is running OK before mapping.
However, having a remap is a slippery slope as after the remap you will want more and more.
I haven't done much else apart from an ITG filter.
Having the 1.8T remapped gave me a taste for it and so I have done much more than stage 1 to my S3 8P. At the moment it is running approx 375 BHP and 390 ft lbs