I have a set of "Brand New" (still in box not open yet) Berk Technology HiFlow cats for the Nissan '07 and up 350z/370z/G35. Asking price is $450
Here are some details form the website about them. If you want pics PM me
"Metallic substrate spun catalytic converters, OBDII & 49 state compliant. Full stainless steel construction. Metallic substrate offers higher flow and lighter weight. Uses advanced spiral wound ultra thin foil. Includes our custom made soft crush graphite collector gaskets for a leak free seal"