Ok, I have an 04 D 5.7 with a 91 octane tune... Im thinking about buying a water/meth kit so I can use 87 and run the 91 tune without detonation. I don't care about the cost of the kit or weather or not it'll add horsepower. I just want to stop at any gas station and pump 87 and still run my performance tune. I also have a Charger with a custom tune for 93 octane, looking to do the same thing, tired of looking for stations that sell 93. I also like the idea of steam cleaning my engine. Thank you for any input.