Any dual tip is going to add some restriction, back pressure, turbulence, whatever....if in the tip, muffler, I have a dual outlet muffler here that has a horrible design for exhaust flow but had to look in with a flashlight to see it.
I really like the dual tip look but not the restriction so went with the same Vibrant tip I had a pair of on my C5 race car, just because I wanted it to look better and not be restrictive.
It matches the Ford oval very well, much better than the pictures shows. I will cut off the rolled in part so less restriction, cut the input to make it fit the 3" muffler outlet and weld it on.
It also weighs less than a dual tip, weight is THE mortal enemy of all things in real performance, sometimes we have to add some to maintain balance due to rules, allowances, etc but always, always, always, should be the top priority.