I needed a bit more power so I bought a Cobb for its ability to customize maps and possibly upgrading my turbos soon. Initially I had GIAC installed and I couldn't install the Cobb over it, the dealer could also not reflash over GIAC, so I had to send my ECU to GIAC to be flashed to stock. A sizeable financial loss. After this, I could install the Cobb with no problems. I have to say that neither GIAC nor Cobb's technical support lived up to the expectations on this problem. I mean, Cobb finally added support for my ECU after a week and a half. And GIAC said it's not their fault.
During the installation, a pump / fan in the lower trunk area kept working all the time, not sure if this is normal or not but it did concern me a bit. When this begun to work, a "DSC malfunction error" appeared on my iDrive. When it stopped, the DSC error disappeared. Could this be something related to the brake/ABS pump ?
Initial driving impressions (Stage 2+ Aggressive):
At WOT, the car has significantly less lag down low, more torque down low but falls flat on top compared to GIAC. It feels like 20-25 less hp but I have to confirm it on the dyno in the next days. Also the engine feels like strangled, the turbos sound can be heard. You hit 19psi in no time, it isn't even needed to push the pedal more than 50%. At 5800RPM the boost is still like 15.5+psi. I can now see that the linear throttle maps do have a merit and I will probably switch to a linear map.
At partial throttle, there are small hiccups at certain points in time, especially when you take the foot off the throttle and then press it again. But I only had 2-3 hiccups at the beginning, maybe the car was adapting.
No error codes thrown after multiple WOTs, which is a relief giving the misfire problems that kept appearing on the forums.
Unfortunately, I wasn't able to log, probably due to the beta firmware (I will try to install a stable version, or I will use the BT tool). When pressing the OK button to start logging, instead of a "logging message", a bunch of logging parameters appeared on the screen.
What concerns me the most is a sound that I can hear somewhere on the drivetrain towards the right rear of the car (or maybe to the right of the engine, not sure) for like 1 second when accelerating at lower RPMs, you can hear this sound and then the car jolts forward a bit. This sound was not there with GIAC, never heard it. Maybe the increased torque at lower RPMs generate noise in my LSD / M3 bushings that can be felt inside the cabin ?
Generally, the tune works better than I expected (aside from that strange sound) although I don't feel 100% confortable driving the car to the max. However, since there are solutions to lower the boost and increase the timing (like GIAC does) with even better results, why work the turbos so hard ?