It's in the back seat area in the headliner. Pop the headliner down by the rear window (held up by 2 magnets) and disconnect microphone. Should help quiet down the interior
I have the same wheel and tire setup mine drives good.. Now on my way to work there's couple roads that see heavy truck traffic and it can feel squirrely on those roads. Steering is a lot more sensitive then anything else I've driven though.
I just did the same thing Chef did and also put in a k&n filter at the same time.. So far my iat's are noticeably lower at idle and in stop and go traffic.