440 what am I missing here?

The eas
Not enough info however if you follow Andyf and everything seems not ready to fly apart stick it on a Chassis dyno for a couple of pulls.

Getting 600hp is not always text book. The easiest way is CI however even that can fall short with a bad combo. But yes, if you had 600hp you would be sideways in the street at will lol....

JW
The easiest, cheapest way is a shot of nitrous