Big Gun Exhaust 13-43823 EXO Full SystemBig Gun Exhaust 13 43823 EXO Full System EXO Series came about from a realization of the need for a bigger and better muffler that could handle the huge demands of the larger, more powerful MX motors. The EXO Series is our ground up approach at just that. A unique hexagon shaped aluminum muffler and stainless steel coned inlet allow for significantly more volume, delivering a louder but tolerable deep sound while also decreasing heat. Light weight