We have a couple G37 coupe stillen catback systems we need to move. Part number 504400. Fits G37 coupe, but will not clear the convertible. Stillen has since updated it to work with the convert (504401), but these are the older versions. Dual wall tips
G37 coupe exhaust
$1100 shipped within the US, add tax if in Texas.

I also have one G37 sedan kit as well
part number 504377
G37 sedan cat back exhaust
$1000 shipped within the US, add tax if in Texas.

Email is the best contact at infinitiparts@sewell.com