Hey everybody,
I would have needed the exact measurements from these “barrel” tubes:
(what the red arrow shows).
Like diameter and length.
Any help would be much appreciated.
Thank u fellows 
Dude, the dimensions are clearly posted in the Equipment Plans section, under the Equipment tab on the top of your screen. Stefan’s plans detail the length and diameter of them. Just check around a bit.
Those are called Injectors.
As Krenzy said, have a look around a bit and then if you still have questions look around again because you must have missed it.
they’re right…check out the top tab Equipment then Equipment Plans