Exhaust Diameter on 69' Mustang

[AGStang1969]

So I've got a 69' mustang, not the boss or mach 1 though. Engine size is a V8 302 with dual exhaust. I'm looking to put in a set of x pipes with a pair of dump off valves on it so I can open and close the headers via a switch inside the car. The only thing I don't know is the actual diameter of the pipes. Now I'm guessing that they are the stock pipes, but I'm not quit sure. Is there some way that I can measure the diameter of the pipes without having to remove them or does someone know the diameter of the stock pipes on this year?

 

[alexb_]

Measure the circumference and divide by 3.14?

 

[AGStang1969]

lol. I thought about that, but wasn't sure if that's all there was to it.

 

[j_lutter31]

yep, thats all ya do....circumference = pi*diameter