I just tried an experiment the other day, I installed the silencer in my Blitz cat back and now the "Boxer Rumble" is all but gone. Now I have what sounds almost like a jet engine or a loud air pump at maximum output. It is actually an amazing sound that is very unique and loud at 5K-7K RPMs. Has anyone else heard this exhaust with the silencer in place? I loved the sound of the open exhaust, but now I can drive slowly and quitely and then open it up and expell holly terror on the unsuspecting. I will try to somehow post a video clip so you guys can hear what the heck I am talking about. I guarantee that you will all be amazed by the crazy sounds my STI makes now.