In light of these postings, removed the firewall foam bit on my 08si. Easy to do as above...just pull aft end tube from firewall and undo clamps. Removed foam; rubber grommet came out with tube at the time byw. Re-installed grommet into firewall, and used some rubber grease to replace tube...it went in much easier and I did not risk pushing the grommet inside the firewall where it would be gooooone forever. Drove it, and honestly preferred the sound of the Stebro exhaust and was not enamored with the extra "woosh" of the air...too muscle car-ish for me. So went back and put foam back in and now am actually happier with quiet motor, and deep exhaust.
I think they added the sound generator, rather than take away sound deadening to avoid the Mustang, Camero thin metal and door sounds. The Bimmer and others are bit more quieted from road noise, and thats kind of nice...any less materials and car would be a bit "thin" sounding [mixed metaphor but you get the point].
