hey chucky, how the hell are you getting 30 on a 970 0on ultra :::

about sound, there is a bug, you have to set your output in windows, or the game keep switching them (stereo,surround), this causes dialogue to play low.
the settings that take the most FPS hit, water phisics, ultra can take up to 15-20 fps, i set mine to one lower than max, but you can take it to medium, you can only really see the difference in water crossings where the current is faster. Set tree quality to medium, high and ultra just bump the bump map a bit, but from a distance its the same bloody thing and there are TOO MANY trees in the game. tree tesselation is also a performance killed, also its bugged, you can see through the trees. looks nice but eats 8-9 fps
Global lighting can be set to medium or high, the difference is minimum, water reflection can be put to medium as well, the reflections are blurry regardless. Volumetric clouds can be set to medium and depending on how often you look up even low. unlike odyssey where this affect the amount of cloud formation, in RDR2 this setting controls the resolution the clouds are rendered. Some people recomend loweing fur, i set to ultra didnt feel any impact, but you know i have a 1070ti wich is basically a caped 1080.
shadows to high will give you a boost, i use it on medium bexause i like soft shadows and it feels nice. set the grass to high or medium as this affect the amount of shadow each blade has and how far they show up.