I have no idea on fuel system, I really don't know about 6.0's. I have swapped these nozzles before and had the inejctors apart and that's about all I know.
This would be a DIY Kit. You take your injectors out (like a 3 hour job?) swap to the new nozzles (less than 1 hour) then put them back in.
These nozzles are rated to flow about 100% over stock. I do not know what the stock nozzle size is, but these are Brand New made to factory specs but with larger holes. EDM'd new. They are flowed by the manufacturer to within 2% of each other. I've sold thousands of nozzles for the PSD from this same supplier with excellent results.
I've never done a Cummins nozzle swap, but I don't think it's as easy as those. You still have to take the injector apart, but it's not bad at all, way easier than a 7.3 injector. You just need a T-10 Torx screw driver, 4mm socket, 1 1/8" deep well, torque wrench, bench vise, and some rags. Takes me less than 1 hour to do the swap.
The problem with getting good reports back is I need people interested in the first place to actually do the swap. Those that have asked won't pay the $650 - $700 so I never went any further with a Kit.
I'm not really interested in doing the work for this, I have for some local guys, but it's just too easy and doesn't take that much time. It'd be a waste, IMO, for you to send them to me with all the shipping and down time when you can spend 1 hour yourself and be done.
If any of you guys are interested please email me and I'd be happy to take care of you to get a few Kits out there.