I have the FSWerks system.
It's a bit louder than stock. At idle, it's very quiet. Step on it, though, and it roars (or squeaks, not sure a 1.6l can roar)
I drive 70+ miles round trip to work, 60 miles of which is freeway.
Anywhere between 65-80mph, there's virtually no drone.
Very happy with my purchase, and I actually picked it up used (2500 miles on it) for $300 on eBay
Score!