when making single colored tees, you can't get any brighter colors then the max white default tee (192, 192, 192 head - 114, 114, 114 feet) because the colors are multiplicative. so all head channels will be multiplied by (192/256) = 75%, and feet colors by (114/256) = 44.5%
when using the same skin from the TW client the looks will look off because of this, as the TW client appears to use true color.
maybe just a white default skin might be useful, or a different color setting algorithm, like a button that says "true color" in the client might be useful.