So I did my own exhaust pipe after my egr/dpf delete. I noticed the stock down pipe has a catalyst of some type on it. Whats the purpose of that and do I "NEED" to remove it?

btw my truck is doing about 25mpg on hw empty and 18 in the city

 

It's the catalytic converter. Not as problematic as the dpf itself but most people get rid of that too while doing a delete.

 

If youre gonna do it, do it all the way

 

Does getting rid of everything on the exhaust effect the engine brake? I thought that it ran off of back pressure.

 

I don't believe so. You can install one on a 2nd gen 24 valve no sweat.

 

Nope it's the vgt. Deleting everything makes it sound cooler ....if you're into that.