Yes they can - it alters boost by feeding fake signals that fools the ecu into thinking it’s lower than programmed target under load - the ecu responds by raising boost in turn actually being higher - all done in a controlled manner and monitored if jb4 is used.
All these metrics boost timing fuel etc is recorded by the ecu...it’s deep within the service metrics of the car so they don’t see this u less they look for it - nonetheless it’s there - service isn’t looking thus they don’t care.
Also some times you will throw a code if it’s too aggressive or if like flashing goes bad - even though you can clear the code, it’s still there behind the scenes recorded - I just updated and through a code
none in 3 years but a failed update did it... no issues as it finally updated but now it’s there
Anyway - I’ve had it 3 years even leave it on for service as I am lazy and my dealership doesn’t care ... but that’s mine.
If anything goes wrong with the motor it’s always a risk and all the data is there for them to determine what the state the motor was in when it failed - though small risk as long as you don’t push it. Jb4 is generally well tested (on the 3 and 4 series not sure about this one) and never heard anyone with issues - and I have been active for many years in the community.
But such a huge difference is worth the small risk
