Mine is just a standard AUM 150bhp, not even as powerfull as the AGU which is 180bhp (though imo its a better engine) and even that blows other mk4 1.8ts out the water. The fastest car thats properly tried to have a go with me is a focus st, and I blew that away also, was pretty even up to about 40-50 but the AUM just kept pulling when the st slowed
I'm not bragging as I got no real clue how fast st's are, but it put a smile on my face

this was on my way to work and it turned out we both worked in the same terminal so he parked next to me and asked what it was

All i've done to mine is stage 1 map, jetex 16v system, sports cat, cold air induction, coldside dv relocation. Again I have no real clue as to how much difference this has made as I never drove it standard, all I know is its fast as f**k and a lot of fun

Anyway back on topic, there is a good list of gearbox codes and ratios etc on clubgti, the 16v 02a (DFQ) is obviously better suited to the mk3 shell as its from a mk3, its also imo the best ratioed (is that a word?) 02a box or even 02j
As I said before though, if you ever do get an 02a, try and fit it with an 02j shift tower and an 02j shifter, its so much smoother and feels a lot nicer than the 02a.
I saw kells saying welding is needed to fit the 02j, but I'm not sure if thats right? Apologies if I'm wrong but I think I remember asking the same thing when I was doing mine and was told its just a straight swap the only bos that wouldnt fit was the vr6 as its different bell housing?