At the request of danewilson77, I will review the AFE Intake.
To begin with, I can't compare directly to the factory intake as mine was shot from the accident and epoxied back together; needless to say it wasn't working as well as it should have been. However, I can compare it to my dad's (330i ZHP) intake.
Performance: The car seems a little peppier and seems to respond to the throttle better, in terms of actual performance gains I'd guess about 2-4hp/tq. I'm sure the car is breathing a bit better as well.
Sound: My favorite part! The sound is the same except in two situations - over about 4k and more than about 3/4 throttle at any RPM. The sound is, simply put, awesome. It gives a low, throaty growl to the car which it definitely did not have before. It is also a bit louder.
Fitment: I don't know if my is just old, but the fitment disappoints me - not sure if anyone else has this problem. The intake hits the Xenon Ballast, Expansion Tank, and the Upper Radiator Hose. Not to the point where it's going to break anything, but it is annoying and it rubs. Also, the top cover is a major PITA to get on (comes off fine). The bolts never seem to want to line up well enough.
Conclusion: Assuming AFE fixed the fitment issues, this is a very good intake. You will experience some performance gains and the sound, as stated, is pretty awesome. However, with the BMW Performance Intake currently at its competitive pricing, I would have to say go with the BMW Intake. While I can't compare directly, I assume it will give very similar benefits while fitting perfectly and looking good - two things the AFE, in my opinion, lacks.
Here is a picture of my AFE Intake:
And here is a video comparing the stock intake to the AFE Intake (stock intake first, AFE second) and some pulls. However, the sound in real life is significantly better than the video can convey.
I hope you enjoyed this review.