Does anyone know if the stock 2005 KX250 exhaust pipe is single walled? Some of the KDX pipes have a built in metal mesh / sound-dampening thing. I am guessing the KX pipe is made without that. Does anyone know? What about an FMF Gnarly pipe (or other aftermarket pipe)? I am planning on cleaning the insides and am trying to figure out if that is a factor. Thank you.