I use polythylene as well and had a hard time tracking down restriction numbers. Mine is 1/4" BevSeal Ultra 235 which has a special liner (I think its PET). This liner caused my restriction to be .4 PSI per foot according to the manufacturer. I don't expect that is the case for all polythylene though. I would HIGHLY recommend the same type I used for a long distance run (mine goes from basement to kitchen). Even at that distance I had too little restriction and had to use epoxy mixers. If you're going on a shorter run, you might consider this but I'd recommend something with more restriction.