We had cockpit cushions with piping. I'd straighten the edge and 2 weeks later it would be rolled around the front and I'd have to unzip it and bring it straight again. I'm looking at my sofa across from where I'm sitting and the piping is rolled over and not making a defining edge. I think if you're adding piping there needs to be a way to keep the damn stuff where it's suppose to be and in a straight line. Perhaps a button or two in the middle of the cushion or some other method to keep the material from moving.