are there or are there not different injectors for e-series xr models??
i have some that supposedly from el xr6; they have the numbers 280150790 and 666 in the top right corner on one side, the other side has 94da(head designation?)... are these xr6 injectors or do all falcons use the same injectors...?? have read on here that they are the same... but why have bigger pressure regulator, valves, cam, springs and ports and not bigger injectors....????

the XR6 injectors are the same as the std injectors..

that sux. thought they'd be bigger. slightly at least.. what is the 666 designation? the ones on my car have 664 on them (above serial number 280150790)..?

Yep sexyr6 is on the money, XR6 injectors are the same size as standard ones in the e-series 6's. Wouldnt have a clue about the differing part numbers but its more than likely the same size. The injectors from an AU are slightly bigger though. From memory standard e-series injectors are 19lb whereas AU is 21lb or something like that

The 66x number is just batch/lot number. The xxx 790 number is the Bosch model designation, not the serial number. Both I6 and I6HO engines on (later anyway) E series run 790 injectors.

Injectors aren't like carby jets. Bigger injectors are pointless unless you're using nitrous/blowers.
The ECU controls the pulsewidth so the XR6 ECU just opens the injectors a bit longer if it needs more fuel.
The only reason to get bigger injectors is if the engine is modified (a LOT) and the stock injectors can't deliver enough fuel even near 100% duty cycle. Bigger injectors often mean worse spray patterns which is not ideal.

It's also my understanding that when you run higher line pressures, slightly more fuel is delivered for a given pulse. I think this is exactly why the fuel pressure regulator is 300kpa on the XR6. By running higher pressure, the injector sprays slightly more fuel. Perhaps it was better to do this than to run the injectors longer in the fuel map. Can anyone confirm?