I have an '02 330.

330's manufactured prior to Sept '02 (mine) are not Sirius "ready". After
Sept '02 are. IOW, '03's should be OK.

I suspect the 325's are the same. Call your local BMW dealer and have a
service person look it up. I have found that a lot of them do not know
offhand, to my detriment.

First I was told yes and scheduled a service visit to install. When I got
down there I was told, "Oops, sorry...blah-blah-blah"

Of course "oops" doesn't makeup for the time I took off from work to take it
in....  :-(