Is it ok for the muffler to touch the fiberglass engine cowl? Will it burn?

You really want to try and avoid it touching the cowl. It won't burn the fiberglass. But the vibrations will destroy the cowl pretty quickly over the period of a few flights. Especially if we are talking about most "fiberglass" cowls in today's ARF's. The fiberglass is pretty thin and won't stand up long

Ken

Ken is correct...all you have to do is cut a hole in the cowl just big enough for what ever part is touching the muffler....you don't have to cut a huge hole for the whole muffler.....
Make sure to avoid square corners as cracks can form at the corners

Ok thanks guys. I will fix it.