no expert but I've seen people gets some sort of fault on xdrive BMW (2004 and up) after switching to staggered setup. The xfer case on xdrive is electronics and can pickup any slight diff between front and rear axle speed, like you are slipping in slippery road but if the condition persist that xdrive will tell computer something wrong (how in the hell a car slipping for miles constantly buffle the xdrive, for example). Just be careful picking up tire ratio that's all.