IMHO the ZF tune is being way over hyped and clearly some tuners are capitalising on this. For the money you pay, in most cases $500+, I can't say it's the best value for money. Don't get me wrong, the firmer shifts are great but definitely not worth the issues that the new X3 firmware updates have caused with flashing (error 1034, several flash attempts etc). My tuner told me "Just don't change the tune"; yeah awesome, I now have an $800 paper weight all because SCT's R&D is substandard, not to mention the now defunct X2. SCT has questionable consumer ethics.