67 396 Exhaust Opinions

[67SS396]

We have a 67 SS 396 Camaro that we have been working on for my wife and I would like to buy her an exhaust kit for Christmas.

I am looking for opinions on should I buy 2-1/2" or 3" ??

I know she wants dual mufflers (most likely flowmasters)
New headers (will get her ceramic coated if possible for heat reduction)

So I am thinking about just buying her an entire kit and giving her something to smile about.
This has been an on-going project for a couple years now.
The car has recently received new quarters and door skins.
The big block was pro rebuilt with a mild cam.
The car was actually on a rotisserie so now its all clean and shiny underneath.
Seats are all re-done and ready to go too.