I dont see why tuners would be upset at someone decoding the ECU to read the data on it??? After all its not the tuners ECU design and hence not thier copyright to protect. Sure they might not like extra competition if someone starts offering a cheaper data steam monitor/logger but thats just business and tough titties.

Pectel/PI might get upset but surely that depends on the exact license for using a ECU programmed by them. Im not even sure if mid 1990's software licenses were included in the car documentations and im not convinced merey decoding something constitutes a copyright breach.

Sure, decoding a tuners encrypted chip and copying software is a different matter completely and obviously a copyright issue with that tuner.