Gotcha. BTW I gained the 3 mph and mpg vs having the flapper wedged open with the stock muffler, and then went to the magnaflow and cut out the flapper.
That sucks about the v4 helicopter sound, but if you have it wedged open and are fine with it then sounds like you'd be okay getting rid of it. Maybe take the flapper home and keep it in case you want it put back in.
I just personally hate the idea of having the flapper after taking a good look at it after it was cut off. Even wedged open it takes up a considerable amount of space in the pipe.
Your truck your thing, just tossing out my experience with removing it and looking at it in my hand and thinking holy crap, even open, that's a big restriction. (keep in mind the restriction to flow wont just be from the physical size of the flapper, but also restriction of air trying to get around it and the disturbance in flow, add the physical size and the flow restriction together, makes for quite a bit of a restriction)