I was under the impression that new injectors are not available and all Cat supplied injectors are remans with full warrantee. A friend of mine with a Cabo and Cat C18's changed injectors twice over the last several months and all were Cat remans because new are not available; he wanted new...went with new injectors. Given CAT's hourly rate, which includes travel to/from the boat, decided to get new so they would be covered under warranty...
If you purchased "new" but they wanted the cores back, then I suspect the "new" were actually Cat remans. Could be wrong however; seems a trend lately.....