Originally Posted by Golden3ye
I really want to put jb4 on my N55 lease but am scared that when I give the car back or take it in for service they will see some code that indicated it at one point had a tune.
Dealers cannot find those sort of codes. The ECU would have to be copied and sent to BMW in Germany for a major analysis. Which dealers do not do on a lease return. They only do it if there is some major issue such as an engine blowing.