What is the thing right after the cat? Its like a smaller version of the cat...

 

As far as I know you have a "Y" pipe, then a cat, then an intermediate pipe, then a muffler, then a tailpipe.

 

Might be a resonator, it may depend on the option package that came with your truck. It would be there to reduce resonance inside the cabin.

 

Ok so basicly I just wanted to know when I replace all this will I need to replace that. I would think removing it would help alot too because it will offer more air flow.

 

Can you get a pic?

 

I will see if I can get it lifted tonight and get a few pics...