I am pretty sure the 'AC Schnitzer' chip that was in my parts car was from Ebay. The car pulled pretty hard and didn't have a rev limiter (that I found at least). Was in a '90 325i.
Hope that helps a bit.
Currently: 2002 C5 Z06, 2004 A4, 1991 318i LeMons car, 2012 M796, 2003 TT600, 1976 XS650
PM me for your sidewinder (laser cut) key blank and cutting needs. Have OEM pre-ews keys and replacement shells.