Exhaust Crossover Tube?

[VmaXXX]

While poking around on the net I noticed Akrapovic offers mid-pipes that are connected by an "interference crossover tube" and (obviously) sets that include no such tube.
Is one design considered favorable over the other?
Also, are Nash's flashes crossover-tube specific?

 

[ShawnD]

Can't say he has a flash specifically for the crossover tube but he most definitely does flashes specific to each exhaust system.

 

[VmaXXX]

After boning up on the subject a little (straight, X pipes, H pipes, etc.) I'm surprised all VMX1700 cat-deletes don't have a crossover between the rear tubes.
Virtually all aftermarket mids tie into the stock head pipes - the fronts of which are fitted with a factory crossover. Seems the front 2 cylinders would have different velocity, pulse, and backpressure characteristics than the rear.
No biggie. Just Interesting.

 

[Jgas]

I wondered about this as well. Would an x pipe help a gen 1 in any way?