I started with 304. That moved on to 308. I think that I had 300 at one point. I replaced injectors 2, 4, and 8 if I remember correctly. It seemed like my issues were more on the passenger side of the fuel rail. Since you are getting multiple codes, it sounds more like fuel pump rather than individual injectors. Just a hunch.
'06 XK Limited, 5.7L, QD II, Black, 163K
'02 WJ Overland, 4.7L HO, QD, Inferno Red, 126K