I want to fill in large holes in my plastic fairings but what should I use to do this? A lot of people suggest Duramix but which one do I want? I've looked around and found 4040 (semi-rigid) and 4030 (flexible) which are the suggested ones to buy. The holes are on my tail fairing and the upper (the turn signal mounting point), so which one would be the best for these areas? Or is there another product that is better?