there is a circular clip that you need to remove w/ needle nose plyers.
the smaller port is a plug, the larger one is a baffle you need to pull it out, its about 8 " long. after you remove one, start it up and listen to it. i have both of them out and its loud! sounds so sweet!
If you want to avoid the hassle, go to the store and pick up some C-clip plyers. It will make getting those c-clips out hella easy (few seconds) rather than trying to get them out with ordinary needle nose plyers.