Really it all comes down to quality and design.

Performance wise. If it was mandrel bent with minimal restriction (ie, resonators) Theyre all pretty much the same. Given that they all have the same diameter piping.

The main difference is noise and how they handle the heat, along with sudden temperature changes. Ie Going over a puddle on a rainy day.
Then there are brands that make super light exhausts. Really only effective with track cars.

With n/a motors alot of the power (on the exhaust side) lies within the header design and catalytic converter flow. A catback is there to minimise noise and stabilise the pressure and velocity of the exhaust gases.