I never heard a quiet shop-vac. they're just annoyingly loud-doesn't matter what size they are either. just noisy. but they are the best thing to use for sucking up debris, fur, leaves, mud, etc. I got mine at Walmart. stainless steel tank and I think it holds more than 16 gallons of whatever mess I have to clean up. shop vacs are great for sucking up water too.
