100 horse shot of nos for 440?

For every 50hp of N2O pull 2* of timing(6* for 125hp shot to be safe)
Go 2 steps colder for plugs
Low fuel pressure safety shutoff switch
Good fuel supply, you could even run a little higher octane fuel

Cast pistons can take a 100-125hp shot all day as long as you play it safe. To much heat/not enough fuel will melt the pistons