well, you don't have to modify the exhaust system, you can just "tune" it like all them ricers do. how about straight piping it with the factory muffler. remove it, cut out an access hatch in the top of it, gut the interior and install a piece of flex pipe. maybe pack the rest of the empty space with stainless steel wool or high heat fiberglass. then re install the access hatch [maybe weld it all back up, grind the weld down, and spary over with flat black paint] straight piped that is invisable to the eye...