Dynamometer

Use it as fuel.

If you want to do well at Dyno, learn everything you can about Dyno.

Go to as many events as you can.

Play with stuff.

And so 425 is the most of what they will sell you, but...

Dyno testing demonstrates consistently that these cars produce even more horsepower than they're supposed to.

However, for the purposes of insurance, they realized that their cars would be utterly unpurchasable and uninsurable if they had more power than this.

So technically, they produce 425 horsepower.