According to the EPA, you cannot temporarily modify a vehicle’s exhaust noise or induction noise level output unless the device has been fitted by the manufacturer. Why is there no provision for older vehicles to utilise the same technology provided they can get approval?
This is again bias toward newer model vehicles having access to noise control devices to temporarily lower the exhaust noise level output, but forbids the use of such technology to be used on any other vehicle.
A couple of examples of Australian made vehicles where temporary exhaust noise level devices were used in production in recent years are the HSV Holden Commodore VE “W427 model”, and believe it or not, the brand new 2016 Holden Commodore VFII Ute on the showroom floor today, which is advertised on Holden’s page with the quote: “Unleash the heightened aural potential to allow maximum exhilaration”.
The BiModal exhaust has been tuned to provide a balance between a sporty V8 soundtrack and a refined note. The system can also be switched to a non-active mode through the infotainment system!:” To add injury to insult, it also has an induction noise modification called the quote: Mechanical Sound Enhancer (MSE)~ The MSE enhances induction noise and supplies targeted frequencies into the cabin. The MSE operates in conjunction with the BiModal exhaust to provide a balance between exhaust and induction sound character.
Here is a video of the bimodal exhaust system in action. You can hear how this gentleman revs the engine and the exhaust note is quiet. Then you will hear it again and the exhaust note is louder and deeper. That's the bimodal exhaust in action.
HOLDEN HSV W427 VIDEO
Listen at 3mins 20sec of video to hear about its bi-modal quiet/loud exhaust system.
And the new VFII Ute which also uses a Bimodal exhaust system - clearly advertised on Holdens website right now.http://m.holden.com.au/cars/ute?&utm_source=google