This muffler is built for open class 4-cycle go-kart engines that still require mufflers. 

This muffler allows more flow than the 4104 RLV muffler. With fewer baffles and restrictions, this muffler is also much louder and may be banned at some tracks to comply with the noise ordinance. Check with your track before buying. If you are not required to run a muffler, you will make more power without one. 

FITS 1-5/16" OD 4 CYCLE PIPE. THIS MUFFLER IS USED FOR LIMITED, MODIFIED, OPEN, AND TECUMSEH STAR (10HP) CLASSES.