Hmmm....  Banks Six-Gun, right?  :)  I'd take that off before taking it in
for service.  I don't know about over there, but here in the States, this
will get you bounced out of the "warranty" queue real quick.

That aside, the typical way injectors are diagnosed is to use the DRB3 to
shut down each injector in sequence, but this is only valid when the problem
is continuous (or at least occurring steadily while being diagnosed) - the
idea is that the faulty injector won't cause a drop in RPM when it's shut
off, because it's not firing anyway.

Another slightly more non-conventional approach would be to put the truck on
a load dyno, bring it up to temp, load it down, and check the exhaust runner
temps with an infrared thermometer, looking for a differential outside the
norm (expect the rear-most cylinders to run a little hotter than the front
ones).  This isn't something a dealer would be able to do - none that I know
of have load dynos.

What a dealership over here would do is replace all 6 injectors.  However,
STAR (Chrysler technical assistance) has diesel injectors on restriction,
meaning you (the dealer) need to explain to them why you need them, and
usually the truck has to be inspected first.  This is where any trace of a
pressure box would immediately nix the warranty service.