i would NEVER expect a standard 4x4 cooler to cope with anything above 330 BHP
unless water injection is added, you can't tell how quickly the ACT's rise for any given time on full throttle with an ambient above 10 - 15 degrees C
I value my motors more than the price of a cooler or H2O injection

And 438BHP on a T34, wow I wish I could find one that produced that power safely with a C\R of 7.2:1