I was waiting for today to come so I could be the 1st one on the block with the new Dinan cold air intake on my 2000 328i. The installation was almost complete when I had the dealer reverse the process and remove the unit. The problem is with the air filter: a K & N cone filter. The filter is totally inexcessible for service unless the entire front bumper is removed. I was told that the filter is good for 50,000 miles but I still didn't like not being able to clean the filter. The installation process is complicated; the entire driver side headlight assembly and front bumper must be removed in order to install a bracket that holds the air intake tube.
Overall I was disappointed. The entire unit consists of a plastic/fiberglass tube 3 feet in length, one metal bracket, one cone filter, and a few clamps; all for only $499. The process also needs the stage 2 software, which is $399 or free if you have already paid for the stage 1 software (I had). All that plus 3 hours installation at $80/hour amounts to a tidy sum of money.
What the Dinan cold air intake system needs is a "trap door" in the underside panel to easily service the filter. If Dinan had developed that along with the intake system, I would have gone for the system. As it was, I couldn't do it. I suppose I could cut my own hole, but one needs to be very careful of water entering the enclosure, as the filter is low enough to suck water into the engine if one drove through high water.
For now, I'll stick to the stock airbox with a K & N air filter.
For the record, the intake system is of the highest quality. I don't fault Dinan. I fault myself. I want a servicable air filter. The dealer was super in dealing with the installation/un-installation. They only charged me $60 for about 4 hours worth of labor. They were very understanding.