My own 2005 was a final build (March '05) and had the upgraded one fitted from factory. Its a bit hit n miss when the changeover happened, but most 04 built cars seem to have got it. Things are a bit cloudier for 03 built cars.

I did replace mine anyway with a brand new one as a precaution when I picked up the car. I only did this as the car had the 5 year BMW service inclusive coming to an end when I bought it, and me being a fussy shit with preventative maintainence and not being around for the 4 years previous servicing by BMW, felt for the price it was worth doing. It was at a time I replaced the EGR also as I wasn't happy with the movement of the piston due to previous buildup inside. Even when cleaned up, the piston was never 100%.

Report back on how you're getting on and we'll take it from there