Running no muffler

[Vexy]

I plan to run my 4.0 with no muffler.
What is the pipe called that will connect the gap after removing the muffler?
The ends are slightly larger so it can slide over the stock pipe...Any help?

 

[RollinWOT]

It's called a "straight-piped" exhaust. Just be sure to use a set of good quality exhaust clamps and hi-temp locktite on the clamp bolts and you should be good to go.