Noticed when I started my bike up the other morning that there were some leaves moving around underneath it. I thought it might have been a bit of gas escaping between the centre section and back box, but a little ferreting around underneath revealed a little hole in the bottom of the exhaust (literally the lowest point of the main black section, pointing downwards) out through which some exhaust gas was blowing. This hole looks like it is supposed to be there, and is perfectly round as such - perhaps a drain hole? Just seems odd that exhaust gas can find its way out through it. Is this normal/known?
