We've seen graphs from GSR Autosport with pretty high peak numbers. It's made me raise my eyebrows. Anyway, I've received e-mails on this topic and considering how N55 tuning is progressing I thought it was interesting:

Just yesterday we had an old time member come to us with a 535i, previously flashed with GSR. After his car got updated at the dealer, it started to missfire and cutoff at higher rpms with GSR tune. After 4 failed attempts to fix the issue, they stopped offering support for BMWDoubles and even declined to flash his car back to stock. After we reflashed his vehicle yesterday, all problems went away and he is a happy camper. After further investigation and checking version numbers of software, it was obvious that GSR used v54.3 calibration base on a v55 software update level. Since these versions are not cross compatible, BMWDouble was in real danger of doing serious damage to his vehicle. This is not how tuning industry should be done. A tuner that actually cares about what they are selling will always rebuild every tune from scratch for every update and patch that comes out and not sell an outdated calibrations. If you are buying product, we believe there should be full support available, especially product being a software code.
Isn't that a huge screw up? I mean, shouldn't a tuner know what software revision they flashing? It should be basic stuff.