I have a 2007 Honda crv. I want to take the muffler off. I just want to know if there are any dangers to this. And how likely they are. I don't want recommendations, just facts.

the main "danger" is that with the muffler off, exhaust fumes will be directly under the car and have a good chance of coming into the cab. it will also be loud, possibly illegally so. the engine will likely not run well because it requires back pressure from the muffler. you will get check engine lights also. I doubt if a short period would damage your valves, but a long period might. all in all I would say that it is a bad idea and that is a fact.