Hear air flow into a running diesel! My 70+ year old ears can’t even get close to hearing that but maybe it’s because of my tinnitus after getting chemo 15 years ago. I’d venture to say that even my 50 year old ears couldn’t hear it. I installed the RU-2450 two years ago and never had a problem with it, although I can’t tell if it made anything quieter.If you can hear air flow into a running diesel your ears are way better than mine. The original ERicson-era Universal filter was metal, stuffed with metal mesh. They have deteriorated by now and should be tossed in favor of something new.