hello,
i want to try to tune a peugeot 407 1,6hdi. i have read many things about it and now i dont know if it is 100% needed to read and write via BDM. i have read that vio OBD it dont reads all data but via BDM it reads all data from ecu. what do you think guys ?

sorry i am new to all this maybe this questions are really nooby :D

thanks