Am I wrong? You have it, I don't.
It is my understanding that there is a seperate box that ties into the ECU and the MAF, etc... Being a seperate box, I call that a piggyback, rather than a fully reprogrammed ECU..
Both ESS and AA don't use external boxes, they reprogram the existing computer. (from what I understand)
'01 330i with some Dinan stuff
'04 C320 4-matic Sportwagon
** Sig image linked to restricted directory causing a password pop up **