That 452rwhp car is the exception and not the rule. It was also dynoed on a Dyno Dynamics which reads higher than a Dyno Jet. Our local dyno dynamics reads higher by 20-30rwhp. Most people dyno something crazy, but their trap speed never matches.
No new numbers ever came out for that car, and it never trapped 120mph+ like it should have. Seems like a fluke dyno.

But look at a BIG hydrolic roller or a solid roller to get those big numbers on the dyno/track.

 

Also consider your compression, a jump from 10 to 11 to one in compression alone is a 2 to 3 percent increse in power , on a 400 horse motor that is 12 hp or so increase just from compression alone.

 

ws sick I believe jumping from 10 to 11 is only a 1.5% increase. If money permits focusing on the VE w/ a custom intake and headers combo would yeild a higher % increase.

Just thermal coatings should get you there w/ a decent setup. close to 10% increase w/ just the pistons and chambers.

 

Here's a nice little compression ratio tool.

http://www.btinternet.com/~mezporting/compression.html

Every little bit helps.

 

Well my C/R figures out to be a little under 11.5:1 already.

 

That should be plenty to get there, you may have to spin it a little over 6500 to truly get there with the big heads, but compression and cam will assist a big set of heads.