I've just come back to the list from a few years break. I just traded my 97 GTP for a new Greystone Metallic GXP and love it. Just a little sad since my 97 was still in great shape and ran well.
First, the V8 sounds good from inside at low rpms when accelerating. Cruising on the highway, it's quiet not like my 97 with Flowmasters and the droning. To me is sounds like a Mustang. Haven't let anyone drive it so I don't know what it sounds like from the outside except for remote start (I can't find the throttle linkage under the hood to rev it).
Austin GTP: You probable went to the same dealership I did and I might be the guy waiting to figure out what color. They don't know anything about the GXP and since they don't have one, no one will trade and they put me off for days trying to get one. When I first when in, they said they could get one for MSRP, but I used GMBuypower and got invoice quotes which they matched. I just drove my 97 to Dallas (they guaranteed a trade in value without seeing it) and drove back in my GXP. After that, they called saying the color I wanted was bought (yea by me, those idiots).
If you want to see it, we may be able to meet up.