The Double wall Quad Tips are offered on the ZL1 system. We do not have this for the Standard SS or GRNDFX. Now if you Change your Valance to the ZL1 then this would work. The GRNDFX valance will not work being the centerline on the Exhaust opening is different to the ZL1. So if you were to get the ZL1 Rear Valance You could purchase from the X-Pipe back on the ZL1 System and it should fit right up. (the ZL1 and SS System leads are different from the X-Pipe Back). Hope this helps on what your looking for.
Thanks Chris
Chris@Stainlessworks.net
8001-878-3635