Although a very extreme mod if you ask me, but the 2010 Mustang has a “sound induction tube” to pipe more resonant intake noise into the cabin.
2010 FORD MUSTANG QUIETER WHERE IT COUNTS | Ford Motor Company Newsroom
Mustang also features an industry-first Induction Sound Tube (IST), which enhances the driving experience by piping the sound of the induction system directly into the passenger compartment.