A lot is made of pop pressure, but I found 3 injectors in my 1984 300D were for an earlier non-turbo engine. They were marked thus and popped at 1600 psig. The other 2 popped at the proper 1950 psig. I swapped in a set from my failed 1985 engine. Didn't notice any difference in idle noise, certainly not as much as I notice between using fossil diesel and renewable diesel. The later idles noticeably smoother and quieter (higher cetane). I used a pop-tester with electronic pressure xducer and data acquisition, which I detailed earlier. I use shim washers from McMaster-Carr (posted PN's before). You can get finicky about pop pressures, but I doubt it matters as much as having a fine spray.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans