You can chip tune ANY eTDI not just the MK4's.
75/115 is stock AAZ power, but easy to see the 120/200 range with pump mods & an intercooler. The stock injectors are fine for any tuning on an AAZ within reason. FIxing the crank nose isn't an option IMHO, check Libbybapa's profile for the fix.
North american TDI's in stock form 1Z/AHU - 89/149 (MK3 golf/jetta/b4 passat), ALH is 89/155 (mk4 golf/ jetta), AFN 109/173(B5.5 passat) ... i think that's all correct, there is some overlap here & there with the VW half model year changes.
Keep in mind that torque is available from around 2000rpm, so nice for a small truck.
Without a turbo upgrade I's say +20-30% can be found with just a chip tune on any of them, +40-60% tune and injectors & +100-infinity% with tune/injectors/turbo/clutch/...
180hp/300+ is pretty easy for ALH guys to see with a turbo/injectors/tune & then its clutch time, the 1Z's had slightly weaker pistons & maybe rods so aren't as popular for high HP builds.
This guy's got a nice 1Z/AHU build page
http://www.stealthtdi.com/Jetta.htmlThose numbers are off the top of my head, i'm sure others can provide some tuned hp numbers here.
All of the TDI's in e form can run a VNT turbo, the 1z/ahu's need a ecu reflash to newer software for this tho & all benefit from a EGR delete or a upgraded CCV filter system to avoid clogged intake manifolds (something you should check on a used tdi purchase)
The other thing to watch with a used TDI engine is if its out of an auto or manual tranny car, auto's got a 11mm injection pump while the manuals got 10mm. Auto's had smaller injectors though while the manuals had larger injectors. That doesn't matter cause you're going to want some Bosio injectors anyway. Most tunes driven mildly will net better fuel economy too.
Pushing more than a small sedan a nice large intercooler and a upgraded oil cooler are a good idea. Many tuned tdi's run fuel coolers too.
There's a guy promising mtdi pumps from e pumps with a tiny mod, i'm taking that with a grain of salt until its proven.
ebay england always has land rover mTDI pumps, a simple mod to the IP bracket & its installed in a afternoon, I doubt the electronics could be figured in that time. Then you can tune with a screwdriver! Just don't discount the mTDI based off a few posts here, do some research if you're even just a little interested.
thats all i got, time for work...