Almost 100 hp and 60 lb ft increase with a change in intake, heads and cam, not bad until you look at the price for the 100 hp. I'd guess that would be around 450 horses at the crank in ideal conditions. I assume that dyno run did not include the NOS shot.
Actual RWHP usually suprises people quite a bit. Losses through the drivetrain as well as ajustments to atmospheric conditions can really put a damper on those 500 horsepower claims. Where I am at, a 465 horse Hemi will only put down 200 rwhp through an automatic. You want to see some long faces at the dyno...