Im planning on welding up my own exhaust for my 2016 3.7
what is the inner and outer diameter of the stock exhaust pipe?

 

welcome to the forum

I am not sure exactly and don't want to give you wrong information, but pretty sure it is standard exhaust pipe . . . if I was doing the cutting and welding, I would also do the measuring, so I would know what I am dealing with and I can make sure I get the right tubing

 

Yessir, that's the correct answer. Measure twice, cut 17 times. Or something like that I heard somewhere.

Question on my side... why? Just seems extra work to achieve not so much, but hey, I wanna learn!

But to answer... the 2016 V6 has, from the cats back, 2.25" OD pipe, standard thickness, aka 16 gauge or .065". Usually. Then swedged as needed to ensure the upstream tube is always *ALWAYS* slipped over the downstream pipe to ensure proper exhaust flow from one section to the next with minimal to no exhaust leakage where it doesn't need to be leakin'.

How did I get that? Googlin' some of it (for the thickness) and then this particular thing here:
https://www.americanmuscle.com/flowm...e-1517-v6.html
That's a resonator delete, and it's meant to 'bolt on' with clamps to remove that ungodly resonator box under the middle of the car. Swedged at the front to slip on, not at the back to be slipped onto, clamps, done. You can see the pipe size is 2.25" (or 2 1/4" if you'd rather.)

Of course, referencing the swedging, you can always butt splice the pipes together perfectly and seam weld them, but I wouldn't as that induces stresses which can lead to cracks and you don't want that. Don't overengineer this, just use clamps and slip fits and it'll line up *real* nice that way.

I'd go with stainless tube as not-stainless (and the not-right kind of stainless) would be a bad move for longevity.

Can't help you with the headers or cats, you'll just have to measure that out yourself. Still, hope that helps, and lemme know why, I'm curious!

 

When in doubt, google is your friend