I've attached a diagram to show the differences between the two systems (as I have interpreted the tech drawings)..
Red boxes are cat converters, the top diagram is the 2.5 V6 exhaust system, the bottom diagram is the one for the 3.2 V6 (GTA) system.
Chris is running a 3.2 engine with a modified 2.5 exhaust system, I'm running a 3.0 with a modified 2.5 exhaust system..
