Their tone is very deep and smooth sounding. It's a little boomy under 2500 rpm and it makes me not want to go into 6th below 1700 rpm. That means my gas mileage goes down between 45 and 52 mph. Over all, I'm glad I got them, but when I get a full catback, it'll be something else, like Corsa...
It has a deep, smooth tone with no rasp at all. Also, it's definitely louder than stock. I've had mine for three months or so and I'm happy with it. At least for now, lol.
FYI, the body shop that replaced my rear body parts when I got rear ended told me the 50th deck lid cost nearly a grand. Apparently, they're a lot more expensive than the other decklids.
I had that hiccup happen once a couple of weeks ago. I was surprised because I already had 2000 miles on the Whipple and it hadn't happened until then.
I searched Google for rev hang when I noticed mine was doing it. It also seems to help the synchros a little since the computer knows what rpm the next gear will be at.