As of now there are mainly 3 different nozzles people are using. Those being the OE replacement ones, 1.9TD, and GTD. GTD is the higher flowing of the bunch. Several people on the board sell them (I normally sell them but am out for another week or so). The biggest problem you will run into is that you will need a selection of shims to adjust the pop pressure which aren't typically available although many can be ordered from VW. The problem is that you need to know what sizes you need before you order them. I can get shim kits with a selection of all of the sizes but they aren't incredibly cheap. I'm just thankful that I can get them. Otherwise, making the injector halves seal back together can sometimes be difficult and you wouldn't really know it was going to leak until it was on the car if you're using a hand operated pop tester.

i dont have an injector tester but in my expierence used injectors awalys have something wrong with them. i at one time thought i could be frugal by buying a slew of used injectors for pennies each and having them tested, any using only the good ones.

after testing probably 50 used injectors, i managed to find 4 that had halfway decent breaking pressure and spray pattern.

a place fairly close to me rebuilds injectors, turbo or non turbo, for $35 each. its a bosch certified rebuild centre and i have known the owner for atleast a decade. they put new nozzles in, set the breaking pressure and double check everything to make sure its all good.  they can actually take non turbo injectors and bump them up to turbo spec without charging any extra.

What is the final torque setting?

I'll second the overtorqueing. The spec is like 51-52 but it takes more than that to make it seal.

So can one of you guys fix my injectors from my 98 TDI? I had them checked and the shop said 3 popped at 400-500 below normal ( they said about 3100 was normal) and 1 popped at 1100. That cylinder had a melted piston top.

With pop pressure that low I would be concerned that one of the springs may be damaged or something. Raising pop pressure 2000 psi would take an entire extra shim.

I haven't tried the 6.2 injectors myself though.

 
Affecting the breaking pressures will affect your injection timing.  As the injector wears and the breaking pressure lowers, the timing advances.  The spray pattern also declines with age, somewhat offsetting the advancing of the timing (the poorer spray takes longer to burn).

With redone injectors often the max fuel can be increased for more power without additional smoke.  

Andrew

That partially answered a question I have had. How much is the timing affected for each 100bar change in popping pressure? Also, how high can you raise it (breaking pressure) and what imposes the limit (eg; fuel lines, IP, head, etc) I know the higher the better (better atomization and cleaner/faster burn in my mind).