Cats question before I start install

[Ulysses]

Yes,

For the stock pipes to the 3" you will need a reducer. If you take it to a muffler shop, they should have them or can fabricate them easily.

 

[LarryJ]

I've got a set of R/T cats on the way that i believe are 3" in/out. I have a 3" cat-back system to install but my question is about the stock pipes going into the cats. What size are they and will i need some sort of reducer/expander and if so is there a prefab part that i can get somewhere.