Hutch, Can you be more specific as to what I need to look for, or what it is that Holley does and Atomic doesn't? It might also help to specify the deployment scenario where the difference would be actually be relevant. (ie, if the difference is more related to high-end performance cars/ strip cars/ then that difference doesn't really have any bearing on someone creating a mild street performance car or weekend cruiser. I would define these as something below... say 400 HP?) I've read through a LOT of FAQs and know way more about EFI systems than I ever wanted to, but I haven't heard anyone mention this before. The Atomic has ignition timing and idle timing control... so does the Holley. Beyond that and the things you mentioned, going into every nuance of timing is something that probably doesn't really impact the typical muscle car that is a weekend cruiser or mild street performance car. If I missed something, definitely let me know... I can add in a line by line timing comparison. From my perspective... 500 HP is a quite a bit more power than is used by the average street car. Someone designing a car with that much power probably knows a LOT more about EFI than I ever will. Something like that may require somethings that most car's won't. (ie, 80/20 rule... or in this case, probably more like 95/5).