Still reading, I apologize in advance if this is covered elsewhere, but I'm having a hard time determining when you need to correct the checksum. For instance, if one were wanting to write an m-box file to a k-box, I understand that the MAF values would have to be imported to the m-box tune from the k-box tune, as well as setting the offset.

My question is this: Will the above changes require a checksum change, or is that reserved for more in-depth changes? I've been reading now for the better part of the day, and it feels as though a cloud is (slowly) lifting. Kinda like when you learn a second language, the way you feel the first time you comprehend a statement.

Thanks in advance, very interesting reading.

I appreciate the response. Thank you for clearing that up.

Another thing that has me confused is the constant reference to the a6 ecu containing an immobilizer function. It is my understanding that that feature was reserved for MY 2002-up vehicles, and that 98-01 MY's were devoid of this, thus the need to cover or desolder the LED in the cluster that will illuminate if a newer unit is installed in an older model vehicle. Care to clarify?