Not sure really. I got too annoyed with the drone of every exhaust I tried so back to OEM. To be honest the standard system is decent just heavy. Don't forget how much this car already makes from 2.0l. Aftermarket dual exhausts are really about noise and looks. Singles give more top end power and weigh less. They tend to be loud though.
My T1R single 63mm was nice and light but very loud. Definitely helped at to end with a decat as I kept hitting the limiter when I first fitted it and also broke the hill challenge record near work
Not had mine on RR since toda but feels stronger on midrange, they are expensive. I paid £450 for a second hand one.