i can understand spring ratings, but honestly cant see a BOV being rated for horsepower...lets just say a car makes 800hp on 6psig on xx turbo...and 800hp on 30psig on yy turbo. same airflow cfm, but different pipe pressurization numbers.

the way i see it, is you would only need a heavy duty one if a) your running alot of boost or b) you have alot of airflow and need to vent as much as you can quickly to prevent compressor...back pedal (i got you john! ) but some will just use 2 BOV's or even 3 to do that.

but maybe i just have this whole thing ass backwards...wouldnt be the 1st time.