I've got a JB4 G4 piggyback without the harness for sale. I never had any problems with it and it's in perfect shape.
Upgrade your AA AP2 or JB3 for cheap!
'08 E90 335i 6MT. VM 6466g2 kit. Stage3+ Fuel-It with FPR return, BMS PI injection, widebody
'09 Z4 sDrive35i DCT, MHD Backend flash, JB4, DCI