What a coinkydink, I just finished my E46 front door speaker upgrades as well. Inspired by my phenomenal sounding E53 speaker upgrade from this thread.
My mids were in the same sorry shape as Props. I used the TR650-CSI combo. Not exactly a factory fit in the E46 (as it looks like the factory HK system in a 6" driver in the front doors). I made it work but it's not pretty
The tweeter went right into the foam insert just like the E53 front window tweeters mounted.
Here is my mod for the mid to fit in the factory holder
The factory HK mid is 21watt/3 ohms and so is the driver. Seems to take a bit more on the volume slider of my Eonon GM5150 to push them.
All in, the pillows now seem removed from the front speakers and a noticeable improvement in clarity and and crispness of the sound is achieved. Not as good as the C2 units in the E53, so go with those for a really great improvement.
Tomorrow I will tackle the rear door tweeters and rear deck drivers.
Mike