I have some bad news for you... nylon stretches a lot more than you
think it will.
Think you have that shoulder belt tightened down just because you can
bearly reach the Kolsman knob on the panel? Impact at the right speed
and stop suddenly, the belt will stretch enough that your forehead will
hit the Kolsman knob.

T o d d P a t t i s t wrote:
A friend took off early one morning as I watched (pseudo Cub
homebuilt). At 200' the engine failed and he turned back.
It was that, the swamp with tree stumps or the forest. He
would have made it too, if not for the dead tree that he
clipped off (sheared trunk went vertically through the fuse
behind him and out the top) and the berm that stopped him
short. He made it out with a big gash in his forehead from
hitting the panel. Pretty difficult to put your forehead on
the panel when flying solo from the rear seat, but he
managed it. The belt attachment point failed - a tube
buckled.