I think I got lucky with my Cupra R ST as it probably sounds more like the ‘Stage 2’ sounds on that video clip linked to above.
I know it’s got 4 exhausts compared to the regular ST’s 2, but I thought it was just aesthetics tbh and offered nothing functional.
I don’t know if any other changes were done to the system.
I'm pretty sure the Cupra R ST use an exhaust system identical to the Golf R (with identical back boxes even) and it is much louder than a regular ST so it's not just different tips