Howe Dual Mufflers are made for applications where a 2 into one is either not allowed of will not fit. The 3-1/2" Louvered Muffler is the easiest to fit in your system and is also the lightest. Its performance is much the same as straight 3-1/2" pipe. The louvered core is wrapped with a fiberglass mat to help deaden sound. All dual mufflers comewith a 3-1/2" tail pipe.