FMF is the leader in high performance quiet technology and our Q4 is the next evolution in off road exhaust. The Q4 employs intricate chambers, baffles and proprietary multistage packing material making it the best performing quiet muffler available. With the Q4 you don?t need to hear the power, just feel the power! # Developed over years of championship off-road racing # Max Sound output 96dB; most models below 93dB # Constructed from aircraft grade aluminum and high strength stainless steel