Exhaust dimensions?

[Reaper450128]

Anyone know the pipe diameter(s) of the stock exhaust system? The most critical number right now is the size of the pipes going into and out of the first pair of cats, but at some point for my exhaust project (details later, after I have a full plan of execution for my idea) I will need the size of these pipes in addition to the ones I already requested:
1. After the third (center) cat
2. After the muffler

The first number I could really use by this evening, but the rest can wait until my car is fixed. I just need the first sizes so I can see what hi-flow cats I can get for my car (replacing them with the OEM ones is going to run me close to $1000, whereas aftermarket universal fit hi-flows will be about $200-400).

Thanks in advance!