The problem with water/alcohol injection (Damon has a short memory lol), is that the current systems are all constant flow rate systems. They work well for vehicles which have a more or less flat HP curve. This is typical for a turbo. By the time the motor gets up on the boost it is well into the torque band of the motor and HP stays pretty flat until it starts to fall off. I'm oversimplifying it, but therein lies the shortcomings of any of the systems that have been around for awhile.
Now look at centrifugal blower systems. They don't make boost at low rpm and hence don't need the injection to kick in until boost (which is tied to rpm) builds significantly.
Now, what about us? Well, since we can generate full boost at 2000rpm, and the resulting HP curve from there to redline is rather dynamic, we need a system which adjusts according to the airflow into the motor as rpms increase. None of the previous systems could do this. The SMC is an adjustable system, but unless you are going to have someone sit there and turn the knob while you drive, it will never inject the right amount of water/alcohol at the right time. You are either stuck with too much at low rpms or too little on the big end.
Think about that for a moment.