[Rebel1]

There appears to be some confusion in the use of the term "operating system" and some tuners claiming their tune is in fact a proprietary operating system.

Am I not correct in assuming that the various GM ECU's run an operating system developed by GM and deliberately coded to allow changes to "variables" and "tables" and therefore develop what can be called a custom tune?.

To me this is the same as this computer . I'd be pi$$ed off If I couldn't change the video settings, or serial port baud rate, or whatever I wanted after some techo-whizkid did an install. Indeed if I couldn't uninstall a software product when I found it un-satisfactory I'd be mighty pi$$ed .