So the few V8 guys here may be into this.
Bone stock 392 srt challenger dyno
http://www.youtube.com/watch?v=_q6Qs4UGVH8&feature=youtube_gdata_player
Pretty solid rwhp for a NA factory vehicle. Figure dodge said 470/470 so they under rated it basing it on 17% loss for powering other stuff and all.