I have had my valvetronic exhaust for my E46 since the day they lauched the product. I had been eagerly waiting for quite some time and I can say with certainty it was worth it!
I have used it in several different configurations. First with stock headers and stock midpipe, then with stock headers and an Agency Power Midpipe, and finally with Active Autowerke headers and stock midpipe. (The AA headers and Agency Power midpipe do not sound very good together.)
You can listen to videos I took of all configurations though this link. My favorite is definitely with the AA headers because of the tone up at the top of the rev range. There is a slight amount of drone between 2-3k but worth the trade off for the V12 like note you get. Whichever configuration you go with will be a significant improvement over any other section 3 in the market today.
Lastly, the tips were slightly misaligned but with a drill bit, some tapping fluid and a little patience it's quite easy to correct. My system now looks like it left the factory but sounds a million times better.
Overall I would undoubtedly recommend this system to anyone with an E46 M3. It gives you sound flexibility that is not available with any other system and can be tailored, quite dramatically, depending on how you configure the rest of your exhaust. 10/10