Just called a huge supplier trying to get a price on a perforated drain pipe sleeve and he told me they don't sell them anymore. I asked why because I was just in the showroom not too long ago and they had them. He said (NationalAssociation.... of something) has taken them out of their recommendation because they studied it and they could create a "damming point". Is this true? Anyone heard of this? Honestly I always thought the sleeve was pretty unnecessary to begin with.