2003 Honda Civic Loud noise from exhaust system

I was driving on my way to school this morning, when I noticed my exhaust started making a loud noise. I parked and checked out my car and it seems be be coming from the headers/catalytic converter instead of what I suspected to be my muffler. What are the possible parts that could be causing this noise. Its not a farting noise, its more of a steady load roar when I give the car gas.