The factory exhaust sound note on the NSX is conservative. The exhaust note is changed with the "Mode Control" switch which changes the exhaust path in the exhaust muffler section with electronically controlled valves. Even in the louder "Sport+" setting, many owners find the note to be too tame. The most significant change in exhaust tone on the second generation NSX comes from replacing the restrictive factory downpipes with the ScienceofSpeed Sport Downpipes. Replacing the downpipes and retaining the factory muffler section makes a profound improvement in the sound of the NSX. For customers looking for an additional increase in sound volume - ScienceofSpeed offers two exhaust options - a valved (Mode Control changes the exhaust note) and valve-delete model (the exhaust note is the same in all modes). The ScienceofSpeed Valve-tronic Sport Exhaust retains the factory exhaust actuator design to allow the Mode Control switch to continue to function.