The difference in length isn't really noticeable.
The only thing a performance mid section back will do is sound louder. Which spoils one of the car's better attributes.
My Mig currently has a Powerflow system at present. It’s basically joined the two banks together and is a single pipe into a back box which then has a “y” pipe into twin tips. The y pipe has all but rusted off and the system from the cat/down pipes back is a single 2.5inch system as opposed to the factory spec twin 2.5 inch right the way back!
Now I’m most likely wrong with this theory, but I fear it’s strangling the engine (or maybe the difference is minimal) and think that a twin system would allow it to breathe better. Not to mention the fact that it’s rusting, which I find odd for a stainless steel system