As far as i know the trick is to fit SDi injectors to the later L series cars fitted to 25-ZR/45-ZS's as the brake pressure is less, thus allowing more fuel in (tried this on my ZS, went like stink, but smoked really bad, but then mine has been remapped). If you already have an SDi then the only thing you can do is get a set of wingy injectors, and you'll need a spare set to give him to re-engineer, or your car will be off the road whilst yours are done.
Yup exactly as Can'n ZS says. The 200/400/600 injectors have a break pressure of 200 bar whereas the 25/45/ZR/ZS have brake pressure of 210 bar.
So the 200 bar injectors open sooner and close later meaning more fuel gets shoved in per cycle.
I'm glad someone was able to verify my theory on using the injectors as unfortuantly I don't have a 25/45/zr/zs to play with, just my lowly 600Di.
Sadly no-one has yet found a standard set of injectors from another vehicle that'll do the job. You can mod your existing ones to have a lower break pressure (I had 170bar on my van), and you can fit larger nozzles too, as wingy is doing but that all adds expense.
Ok, thanks for the info. I'll stay tuned to see if something interested or I will wait and see if one day I'll be able to buy wingy ones. I am still a studend so at the moment I have not a lot of mine and when/if I'll have them I'll spend them first to buy a front IC and/or an hybrid turbo.