I bought my '00 540i/6 with Dinan exhaust, CAI, and software. I can't tell you what kind of gains the software provides because it was installed by the previous owner, but I do want to warn you about the CAI. I was looking through the maintenance records before purchase, and I saw one bit where it had been put in the shop for hesitating and dying in heavy rain. I experienced this over my Christmas travels when I went through some very heavy rain. The engine went into failsafe mode and shut off. I believe this has something to do with the Dinan CAI because it may have gotten some water in the intake. Be careful with CAIs, even expensive ones. Good luck.