The ND Miata pipes in engine noise to the cabin from the factory, using a plastic pipe from the intake through the firewall. My car has an aftermarket turbo, so that pipe was disconnected during the install, however the parts were still chilling in the engine bay. A 10mm socket and some electrical tape over the firewall and I cut a pound of unused weight out of my engine bay. Race car.

If you still have the stock sound tube and want to remove it, there is a Verus Engineering kit to remove the parts while retaining the stock intake.

Before

Took this junk out

After