I am new to the BMW world. I am the happiest guy ever. I bought a 2005 X3. I was wondering is anyone of you out there know of what I can do to save gas for one but I was thinking about getting a cold air intake and or a cat back exhaust for it. I was told by a buddy of mine that this would really make a difference and since you all have X3's I think someone out there would know if it helps and where I can get something for a good price. I was also wondering about the computer chip. Do they make them and are they any good?