I dunno...I looked inside. I see no flapper

 

You can't see the valve. It's buried inside the muffler. The 05/06 mufflers use the same setup as the 03/04 mufflers. The only difference being the 05/06 muffler is a slightly longer muffler.

 

I have an 05 and this morning I noticed that the exhaust was coming out of both tips while my car was warming up.

Ive never paid any attention to it prior to this morning.
I have noticed that my exhaust sounds a little louder recently. I dont know if the sound at idle/low rpm would change much with both valves open, but my exhaust does seems a tad louder. My exhaust is all stock.

 

Simple test. Take your hand and put it over each tip. There should be a difference in exhaust flow. I believe the left most pipe is always open.

 

I did this lastnight after the car had sat for about 11 hours and I had even flow out of both pipes....

 

Me too...even flow. Cold start after a night of sitting,...and after driving around for a couple hours

 

so whats better or whats the way its suppose to be ?

even flow

or flow on one side and when rpm are high then even flow ??

 

Could be just stuck open, nothing to worry about IMO...I think the flapper just allows the car to warm up a little more effectively.

This. But again, either way is no big whoop. When I have my HKS on in the summer it's free-flowing on both sides. No adverse effect.

 

Tested my muffler last night after a 20 minute drive home. At idle, nearly all the flow is coming out of the driver's side pipe and very little out of the passenger side. Holding revs to 4000rpms resulted in similiar exhaust flow from each pipe.

 

^^ The plot thickens!

 

any1 with 03-04 sedan...

can check there muffler

and let me know if it blows on both muffler when idle.. still been wondering

ive been thinking that mayb my muffler is gloged on 1 side