exhausted :) what system to install?

what does or Hemi like? I use to drag race my 6.1 a few times a year. Currently i have a x pipe homemade style. 2.5". close to the headers. I welded kinda cut outs on the X so i have a straight flow into the X, through the X and on the otherside out to have close to zero restriction. It make lets say a diagonal under the car.
Now i want to go the same way with 3" for next year to have a bit better flow. And move the X more to the rear to have the ends of the cut outs close to the rear tires like on AAR cars.

But I am not really sure if i have a power gain. ok, it is noticable once the cut outs are open. But is 3" ok? Is moving the X backwards ok? Is a cut out behind the X ok? Or better in front of the X?

For street use the X is still connected to the 2.5 dual exhaust ending in mufflers to the rear.
I will add a pic once i have the car on the lift. hard to see on this one.

What are you guys using?