Quote Originally Posted by 89Vette View Post
My shop explained that these are used on transverse mounted engines where side-torquing increases/decreases the distance from the manifold to the [static] pipe location. That makes sense.

Since our engines aren't mounted sideways, the use of this piece must be to dampen vibration down one side of the "Y". I'm guessing that "halfing" the vibration to the "unioned" junction might have resulting in some reduction of pipe vibration.
I am not sure how it can make a difference ether way.

But... i think that I found a reason for the flex section! We have a very LONG y-section, after you apply manufacturing tolerances to it, you might be off by quite a bit! So, adding a flex section allows you to relax some of those tolerances.

It is one thing to fab up a y-section on the car (I do not believe that it would require a flex section). However making this y-section on a jig, might be much easier when you have such flex section.