All the F’s have the same issue from the factory. I didn’t get round to changing the exhaust on my previous ISF, but jumped at joining a group buy for the Quicksilver exhaust as I was determined not to make the same mistake with the RCF & I’m so glad I did.
There is a little drone at motorway cruising speed, but from my perspective it’s so much better than the standard exhaust. However I do appreciate that the exhaust sound & tolerance to any drone is a very personal thing. I’m sure a valved system will be a better more practical option, but it’s also a much more expensive one.
l’m very happy with the Quicksilver & it completely changed my enjoyment of the car, so I hope you find a system that suits, as you will not regret changing it to release the full V8. Good luck👍🏻