[MNoob]

Originally Posted by pbonsalb

I don’t know what is intercepted and altered and sent back. But the midrange bump in RC’s favor and the top end bump in JB4’s favor have to be explained by something and the two things that can make a bump like these are increases to boost and timing targets.

Piggybacks and tunes make power by using up the safety margins the factory adds — leaning the AFR, adding boost, increasing timing. Sometimes there are other tricks like altering cam timing to take advantage of less exhaust back pressure from eliminating cats, but there is no magic. The aftermarket tuners don’t know any secrets that BMW does not know about tuning.

A piggyback certainly can change timing, though as I noted by using “and/or” in my original post, I don’t know whether the RC or JB4 do. I had a Vishnu Procede piggyback on my naturally aspirated E90 M3 that controlled a water meth injection system. It increased timing targets when the meth was flowing.