Help with exhaust system

So I want to buy a whole new exhaust system for my car, and I want to order all the parts separately because they're made by different companies. Problem is, I have limited experience working on cars and I'm basically learning as I go here. So help me out here, I have the headers, after cat h-pipe, and axle back exhaust picked out that I want, what am I missing to make a complete exhaust system, if anything?

What car are you talking about? Are the headers "long tube headers"? Does this car have to pass emissions?

The car is a 2011 mustang gt and yes long tube headers. And I don't need to get smog tested in my state

Then I think you have everything. You'll want to also order an intake so you can actually use that extra flow by getting more air into your engine.

Ok thank you, I actually already have a cold air intake so i got that part covered lol

Or did you mean an intake manifold? Lmao stupid me

I did mean cold air intake, but an intake manifold and throttle body wouldn't hurt if you can swing it.