Andy,
I installed the MPG-MAX system from Snow Performance in my truck. The kit comes with a controller that I mounted on my dash cover. The controller displays EGT/Boost/%of injection. A toggle switch turns entire system on and off. Buttons on the controller are used for programming and pump control (on/off). In other words, the EGT/Boost reading can be used without injection occurring. For driving around town to the hardware store, out to dinner, grocery store etc. . the system is not practical in my experience. But for towing or driving some distance, I like it. I have used straight distilled water, but prefer a 50/50 mix of H20/Meth. I have learned to have injection occur much later than sooner. I pushed the limits of the system setting injection to come on with lower and lower boost and eventually found water in my oil. I wasn't following instructions. By following Snow Performance's specifications, having injection come on later, the system works great. No water in my oil. The display on the controller can be harder to read than a pillar of gauges, but it's good enough to get the job done. There are two programs that are built in: MPG and Tow. MPG is nice and when power mode kicks in, you will notice the power. I have calculated modest MPG gains at best, but then I don't always use the system. Tow mode is great for heavy towing or HWY driving without a load when MPG would use up all the H20/Meth. Tow mode keeps EGT's down and when it kicks up to 30% injection, the power lets me back off the pedal a little without big drops in turbo boost. It's nice when towing heavy. I mounted the 7 gallon fluid tank in the bed.