Here:

http://forums.2gnt.com/dcboard.php?az=show_topic&forum=8&topic_id=56512&mesg_id=56512&listing_type=search

That's the last time I remember Bill saying how much power the RS had. 505 without the DFI... 508 with the DFI.
Now I know he's dyno'd since then, but I don't know the numbers... Dino, you remember?

And yes 505 - 150 is about 355.
I say about because a 150 shot of nitrous will rarely actually give you 150WHP.... more like 75 to 100... so that would put HRC close to 400 WHP.