Y exhaust versus crossover

[Enzo]

Does anyone have a source for a documented flight test or dyno test of a 2 into 1 crossover exhaust versus the common 2 into 1 Y exhaust ?
There is a flight test on the Vetterman site comparing 4 into 1 with different collectors and for 4 individual pipes, but no info is shown for a Y type system like so many S1's have installed.

Thanks for the help
Enzo

 

[race38]

 

[Dennis Flamini]

 

[Ryan Mactaggart]

 

[Enzo]