@DAN_FR it's not about any gain as I've had 630 dekas on my tt. it's more about reliability and the standard injectors could fail at any point just like others who have had injector problems and possibly you too @AJP
I have had injector problems, yes, and it seems I've got another playing up, as you know.
But... I really don't think that's down to them being at their flow limits or anything like that. They just fail. A k03 injector at 290bhp is no less capable than a k04 injector at 290bhp.
If, however, you could show me some evidence or theory that the k04 injector is more reliable (as in less likely to fail, rather than has a higher flow potential) than a k03 injector, well I'm all ears!