I have heard that Z4 ECU's are excellent but i have been told to get a 6j ecu as its better and the best standard scooby ecu to run with a td 05 can anyone clarify please and is the z4 mappable

 

Think you mean 6K ecu,i ran one in my 93wrx and it was great but it kept on bringing up a pressure sensor fault code but i believe a few people have run them without any problems.
Ealy ecus need a daughter board fitting to them such as http://www.enduringsolutions.com/

 

I have a 6k ecu and a z5 ecu which i believe are for the early type ra`s i have ran both in my car and to be truthful they are no different