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These sets are not designed for back pressure. I think the 80X platform is quite tame in terms of noise.
I don't think back pressure is an issue with water, but I don't know that it would do much in the way of noise. In a lake or the ocean maybe, but in a 55 gallon drum, I think it would vibrate the whole drum. If the drum had an open top, I think it would splash the water out. If you had a small opening, it would be similar to a muffler.Thanks ! ... I didn't think of the back pressure.