I have the Ark DT-S. The sound is quite deep and sounds great when you step on it. However.. its not that loud. I've heard the FI exhaust in person and i believe its a bit louder than the DT-S depending on what size resonators.
The DT-S has almost no or minimal drone on the highway.
I wasnt a fan of how the canisters on the trunk.. but the looks grew on me, i personally like the look better over the FI canisters now.
Hope this helps!