Please send us a message with the following information. 1 E30 year and model: (Ex: 1989 E30 325i). 2 New engine choice: (M50/S50 obd1 or M52/S52 obd2). 3 Options: ABS, A/C, Oil level sensor. Our products do not require you to do any modification to this adapter. These adapters are completely plug-and-play for your specific setup. Instructions are included with all of the adapters. We make adapters that work with the M50, M52(Single Vanos), S50(US and Euro), and S52. Options for OBD1 or OBD2 are available. Some sellers will try to sell one adapter that works for OBD1 and OBD2, but they are indeed different. Please let us know if you plan to use a Z3 harness. We make these for all different e12, e21, e28, e30, e34 models. E30 82-85, 86-87, 88-89, 90-94. If you have another type of harness that you would like, please send us a message. If you have any questions, please feel free to ask.