I have an IX RS with Buschur Racing 3" exhaust with the Magna Flow muffler, 3" Cat.

I added a 3" Magna Flow pre muffler but it was very bad to drone around 75mph. With a 5 Spd that is around 3500 rpm. This generates about a 111 hz noise. The APR PREMIUM HELMHOLTZ RESONATOR - 76MM (3"), begins to work at 106 hz.
I expected that would be close enough to get rid of the drone.

I was right drone is gone. Since the path is a 3" straight through pipe with a small port 90 degrees to the flow. There is no performance impact.

Here is the link.

https://www.goapr.com/products/engin.../parts/MUH0015

Mitsuatb

 

You could also have a muffler shop just make and weld a j-pipe (quarter wave resonator) to the length you need based on the rpm/hz. It cost me $50 and the drone from my exhaust system is gone.

 

For the evo with a 5spd 1/4 wave is 38" long. it did not appear ideal for packaging. Likely won't be 304 SS. Also doesn't work as well since the curve portion of the "J" causes early reflections of part of the pressure wave and reduces the efficiency of the pipe.

It can be done, but is best when it is at 90 degrees to the flow ie a T pipe. Pick your compromise. I did the welding cutting and fitting myself so your mileage may vary.

Mitsuatb

 

Could you post photos of where along the exhaust pipe you had this installed?

 

Not easy to photograph its under the car. I installed it not a shop. I put it between the two center drive shaft supports after the cat. On a lowered car you might have a problem since it hangs down about an inch to clear the floor and is tilted down about 5 - 10 degrees toward the drivers side. I welded a two bolt flange to it and bolted it to the cat and welded a short section of 3" to the rear and band clamped it to the premuffler. it is a modified Bushur Racing 3" SCCA Exhaust with a 14" x 3" magnaflow premuffler added to the magnaflow rear main muffler. That did not quiet it down until I fitted this chamber, This is a 5 spd IX RS with no sound deadening. I am coming up on an oil change. So the next time I am under the car I will see if I can get some photos.

Mitsuatb