Cari, I always do a stitchout too but not necessarily on the same material as what I'm going to put the design. I don't usually have a spare sweat to use as a test. (I'm not being catty.) I used cotton and I think it was a lightweight mesh cutaway on the test. On the actual sweat I used the same mesh since I don't think I have any medium weight. Would a double layer of the lightweight have worked? Something else I remembered is one of the members here suggested enlarging a dense design to 105% to help combat the puckering. I haven't tried that yet. I keep forgetting to enlarge it before starting the design.