Any great cummins diesel guys on here?

ok guys
i did some more testing and found if i block off fuel lines to injectors individually
when i get to number 4 injector the truck starts like it should.when its blocked off
so im trying to decide on what injector kits to buy????
probably should replace all 6 injectors, but dang they are expensive!!!
any input on who sells the best kits?
Do i go new? refurbished? rebuilt/reman?
prices range from 1100$ to 2700$ plus core charges

thoroughbred diesel?
dales super store?
industrial injection?

would like all 6 injectors ,and high pressure lines , connection tubes?
the tubes only have 10 miles on them, but most kits come with new tubes anyway
any input on companies you have bought from would be great
thanks