If you keep the OEM manifolds with their integral catalsyers, you don't need the big "3rd Cat".
Replace it with a free-flowing 2.5" (63.5mm) diameter 2bular De-Cat Pipe.
A straight swap for the OEM pipe.
Supplied with fitting kit.
All-stainless construction - no mild-steel flange like OEM!
Combine this with the 2bular 6" diameter system and your car will sound like it looks!