I have used both chips. The jc is better......I have used the dinan in two 325's and was satisfied. It is a very good chip and worth the money. I also use a dinan in an M3(my other half's car). It is also a great improvement.....but then I put a JC chip in my M3....look out! is badder, meaner, and puts an ear to ear smile on you. The best characteristic may be how it smooths out the bottom end rev range. It's plain ol' awesome! The JC chip has an "intermediate" chipboard that the dinan does not have. I can't remember the name or what it does. The only other difference I noticed between the two chips is that the dinan never pinged and the jc chip did ping just once.....Maybe the dinan is a better choice where gas sucks........ Is there really a noticeable difference with the JC chip vice Dinan or Autoauthority? What makes the JC chip so popular? Who's the best source to buy it from?