I have Dyno sheets with and without this piece of crap installed its nothing mroe than a mere fan that BLOCKS airflow and the little air that does make through Swirls WOOP DEE DOO! This is the most restritive piece of crap in the market.. its like breathing through one of those whistles that sound like a little turbo ... my stock 535 pushed out 175 to the wheels without it and 158 with it ..... What the hell is this crap ... thats like those Fuel line magnets THEY DONT DO CRAP!