Um, no. It does work on gassers to. Scientifically proven, plus good dyno results.
Same theory as why your jeep seems to have more horsepower on cold humid days. Colder, and more dense air, makes a bit higher compression, and better fuel burn ~ spraying a mist of water and methanol into the intake instantly evaporates doing the same thing. Lowering the intake air temp, making the air more dense.
BTW my Diesel is an 02 Dodge 3500. I'd love to have a 4bt conversion Jeep, and to be sure, it [w/m injection] would be on there. The wife however will not let me touch her Jeep performance wise, only maintenance and repair.