From what everyone I know that has meth/water injection systems says, you don't get a large gain out of it for the cost. "A good tune can make more power than most half-assed meth maps." -My tuner, Bren G. Unless you are planning on running a UTEC or AP where you can switch maps on the fly, it's not worth it at all. And yes if you run out of meth, you will destroy the motor. Even with the failsafe, it can still cause damage.
+1 for the suspension upgrade instead. Hell, just a set of endlinks can make the world of difference in a daily driver. Honestly, meth/alcohol/water injection isn't worth it on a daily driver. Maybe on a strictly track car.
VF34'd Corvette Killer aka Doug