Funrevn

New S4 owner... been reading this message board for the last few weeks and noticed that there is some uncertainty regarding the exhaust flap. My car is an 06/04 build and has the flap and actuator. So I looked inside the muffler and with the engine off the flap is open. Then had someone hold the engine RPM at 2500 and nothing moved...??? All hoses are their and connected. How strange.

It is my understanding that the original intent was for a good sound at low RPM (open) and not too much noise at higher RPM (closed).

Can anyone confirm this and is it really necessary to plug the hose other than to keep the line clean if you wanted to reconnect it in the future? Oh and why are the two mufflers actuators connected by that green hose. Thanks.

DrGP

I am surprised that your 6/04 build would still have the flaps since the flaps were supposed to be eliminated in spring 04. Nevertheless, if you want to close them off, do this. Pull black hose off of plastic connector where green ang black hoses meet. Take small screw and screw it into plastic elbow connector. Replace black hose on connector. 5 mins tops!

Funrevn

Is it really necessary to plug the hoses... And by doing the mod does it keep the flap open at all times effecting the upper RPM sxhaust note.

Thanks

DrGP

to be honest, I didn't notice a significant difference,but others have claimed to notice an increase in volume? Audi was supposed to have eliminated the flap on the muffler, perhaps they had some excess stock and put them into production?

ColoQuattro

one of Audis tweaks for the perfect car. If I were to keep the hoses unconnected I would definetly plug them. You will have a vacuume leak.