My 86131M is straight fluted from one end to the other just like a glasspack muffler.

Bill

 

thanks WA,,,thats what i was wanting to know.......the 371 that has a baffle has a open chamber about 8 inches long right behind the baffle,so knocking out the baffle still isnt going to be the same as the 131....im sure that open chamber would create something going on there and affect back pressure and sound....................bama