There are on! I'm going for a long ride to listen to them this afternoon. I'll try to take pics over the weekend, but probably won't be doing the wav any time soon. (I really think they don't do much to really provide the true experience of the systems)
They are definately louder than stock at idle and acceleration, and they "burble" the way the old true dual musclecars used to. They are pretty quiet at cruising speeds. The system is very well made, and pretty cool looking - really a shame it's hidden under the car. They fit comfortably between the systems that are so loud that I wouldn't be able to tollerate them and the systems that you have to concentrate to hear much of a difference from stock. You probably know which units I'm referring to.
GHL is at capacity making the things now, and I bet they will be back ordered as soon as more get on the street, and people see and hear them. I got the second set made, and they start shipping to dealers very soon. It's not a huge operation, and you can appreciate the quality of the welds and polishing when you see the product and the guys that produce them.
More when I take some pictures, but I have to go Mothers Day shopping and drive around a bit.