Header measurement

[Kaferdog]

I think I know the answer just wanna be sure.......! what do you measure on a header inside or outside diameter....?...Thanks

[Taylor]

Outside

[DKK Ted]

The inside plus the outside, times 2, divided by pie, add the length of each tube, divided by 4.        OR, just measure the outside. 

Ted

[volkskris]

outside in the US, inside in Germany

[Kaferdog]

The inside plus the outside, times 2, divided by pie, add the length of each tube, divided by 4.        OR, just measure the outside. 

Ted

Ted is that "Apple pie" or "Cherry pie"...?