Hey Whitey,
I have that setup and it is Very cool.
The Tubi is supposed to add around 6 Hp. I have the Powerchip-(Tunned for a Tubi as well)
But I don't have dyno numbers.
The buttometer is happy. The Ears are extremely happy. It is silky smooth music.
The sound is a sweet symphony.
Exhausts are choosen from Sound, not by numbers. The numbers are not impressive, but the sound certainly is.