I have an 05 RS Wagon and did a '02 WRX OEM catback swap.
Minor welding had to be done to align the wrx flange with the RS Cats but after that the installed went on without a hitch....It feels much better now.

Now..when I say OEM i mean OEM...the track/mid (or whatever u want to call it) pipe is the original so it has that "chamber", as the manuals so ambigously put it.

Finally, Here comes the issue...

At deacceleration backpressure between about 1400 and idle..there is a strange chirp sound (kinda like a bird) coming from the muffler tip.

ANYONE EXPERIENCED THIS BEFORE?

Im hopping is the welding done to the flange, in that case a would cut out the complete chamber and just leave astraight through pipe (smoother i hope)...

but, if it's the muffler(axle back)...Im screwed.

paid $100 for the catback and 65 to install it so i consider it to be a good buy.

 

Dump the resonator, you don't need it. Just get an intermediate pipe from Daddy's. hell get a full turbo back with your at it.

 

It is not a turbo...its an N/A RS

the issue is the d@#$ chirp

 

The chirp, beleive it or not, is from the tips on the exhaust. There are two little holes on the ends of them if you look closely. All N/A imprezas with this mod have the issue. WHen I got it done, I didn't like it at first but then I got used to it. The only way to get rid of it is was remove the tips.


If it really bothers you, do what I did and upgrade to the STi exhaust!

 

I can vouch for this also. For a short period of time I ran a wrx muffler on my RS and it did have the chirping sound.

 

Odeezie,
You replace your stock 2.5RS 2005 exhaust by a stock STI 2005 one ??
And The fitting is good ??!!
minor welding or cutting ???

 

I went from the stock exhaust (2002 OBS) to the 02 WRX exhaust to the 05 WRX exhaust to finally, the 04 STi exhaust. The obs and RS exhausts are the same by the way. ANyway, in order to get the WRX exhaust(s) to fit, you need to modify the midpipe a little bit (costs like $20 bucks). They need to roatate the flange and extend it I believe. Other than that, it works awesome. Here is a sound clip of the Sti Exhaust with the modified midpipe with not resonator.

https://home.comcast.net/~odeezie/stiexhaust.wav

 

I just installed an 03 wrx exhaust on my 2000 rs, i cut out the resonator in question but i had to use the old exhaust flange in order to get it to bolt up but other than that clerence is good, all the hangers except for the one right before the muffler work. it has a low end grut.. has a definet rasp to it witch i dont mind. no chup tho.

 

I've installed two of them and the only time I hear the chirp is when I'm sitting in the driveway and blip the throttle or shut it off. Driving down the road there's no way you'll hear it with the windows up and the road noise will be louder if they're down. It's really a non-problem IMO and the car does runs better with it than it did with the old 1-7/8"RS pipes.

 

I take back what i said about the rasp... i just installed a catless "track pipe" and i have rasp like crazy ... round 3foot muffler is on the way hopefully that cures it...