Hi, i have a challenger mt875b with c18 acert engine. I bought 5 reman injectors ,i want to replace it because it already has 7,000 hours in it. But te manufacturer said: “The injectors do not have the trim code because they are manually calibrated within a maximum difference of 1% in the fuel delivery. Caterpillar provides the trim code because their injectors are not manually calibrated. We sold 100+ injectors of this family with no returns from the market.” and “ you need to tell your mechanic to do the same job he does on OEM injectors except for two things: 1) Leave the old trim codes in the ECM 2) He does not have to do the injectors calibration in the ECM.“. I really don't have to change the original Trim codes? it is possible?