I'm no authority, but I've read other opinions that the old style injectors (pre Index 11) are failing due to the ethanol in our fuel. I'm right in the middle of a swap now because two of my Index 07's have failed. $900 later from
www.rockauto.com and I've got brand new Index -12's sitting in aftermarket boxes with BMW logos on them. I read something about the -11 and up having different piezos, something about being internally lubed...basically to handle E85, I just have no clue as to what percentage.