My guess is a vinegar and water mixture. Not sure if ammonia would ruin the paint. If it doesn't it would probably work better.
RainX does work but I've heard they eat away at the wipres, even though they aren't used much.
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GenV GTP engine, 12" Brakes, CAI, 3" DP, HighFlo Cat, 180 T-Stat, Aeroforce Gauge, Front STB, Stinger Fiberglass hood, Reflective Graphics.