325xiT Cold Air Intake Installation
This was a budget installation so I just bought an intake off ebay from Chrome Intakes. Their design seemed sturdy and I liked the 3" chrome pipe and dual cone filter. I also picked up an AEM bypass valve to protect against ingestion of water.
First step is to remove the original air box. Disconnect the air flow meter connector. The air flow meter clips to the air box on both sides of the meter. Then there are two 10mm bolts that hold the air box in place. I forgot to snap a picture of this so your on your own, but you can see the clips on the side of the air meter and the air box bolts barely visible on the right.
Next remove the fender liner. You have to pop the computer temperature sensor out of its clip before doing this (seen dangling). Then undo the two 8mm screw connecting the liner to the bumper. There are then three more 8mm screws at the top of the liner. With a little force and a lot of finesse, you can then remove the liner.
You now can see your fog light and lots of room for an air filter!
Now attached your bypass valve to the air meter. I purchased a 3" bypass valve and it was very difficult to get on the air meter. I am not sure what the next size up is, but it is worth considering. Alternatively you could place the bypass valve between the 2 segments of pipe.
Test fit it all! I loosely attached the chrome pipe segments together, snaked them down to my fender liner opening, then loosely attached the pipe to the bypass valve. I then tested the filter to make sure there was enough clearance. Once I was happy with the fit, I tightened the hose claps and installed the included bracket.
I then tightened the air filter. It fit well just below the fog light.
Put the fender liner back on and your ready to go. Remember to fish the temperature sensor back through its opening. Also, note the clip on the underside, inboard edge of the fender liner. It is tricky to get back in place. I took a peek at the other side of my car to make sure I had it seated correctly before reinserting the screws.
At idle there is a slight "air flow" noise (with windows rolled down). As soon as I hit the throttle I noticed improved throttle response. The engine revved a little easier and felt a little stronger, but I wouldn't expect more than 3-5 hp at higher RPM. I will update my impressions once I have had a little more time to test it out.
The best side effect to the cold air intake is that the engine noise is more obvious. Not annoying or to the level of a new exhaust, but there is a noticeable rumble/growl.