Difference between PD injector variants P1.1 vs P1.4.

Just wondered what the difference was between variant P1.1 and P1.4 PD injectors?, I have seen comments before about solenoid response differences.

My original 520 injectors are
PDE-P1.1/80/520S210

I also have a set of 560 Toaureg injectors
PDE-P1.4/80/560S220

My original plan was to try the 560's or get one of the sets rebuilt with Firad nozzles.

Any advice on the differences between P1.1 and P1.4 will be greatly appreciated.

I heard the 1st generation are the best ones, AC code at the end mounted on the AUY engines. I might be wrong ..

Macradiators.com said:

I heard the 1st generation are the best ones, AC code at the end mounted on the AUY engines. I might be wrong ..

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Do you know what is better about them?.
My idea was to have Firad 50's fitted to my OE PD520's but if I find the smoke bad off boost I then won't have a standard set of injectors to refit.