If you click the link below and look on the photo page for "under car wrx muffler pic"
you will find a pic under a wrc car which shows the muffler can anyone tell me who makes that muffler and the benefits of that weird design of dual inlet single outlet compare to most standard mufflers that have single in and dual out.
Thanks,
John

photo at:

 

I have the same configuration as standard on my sequential twin-turbo Legacy RS (although the muffler make is different). On my car, there's a valve on one of the inlet pipes that can be shut off by the ECU to keep more back pressure in the system to assist in keeping the first turbo spinning longer until the second turbo kicks in (but I'm prepared, as ever, to be educated on this matter by those more mechanically minded than I am ). I assume, on the WRC with a single turbo, that it will keep the turbo spinning longer on the overrun, thereby reducing the time for it to spin up again when the accelerator is pressed again. Sorry, don't know the make of the WRC muffler.

Brian