You gain 1% power for every 10 degrees you lower the carb inlet air temp. So on a 500 horse engine, if you lower the temp of the air into the carb by 50 degrees (which ain't hard to do, as hot as it gets in engine compartments), you will gain 5% power, or 25 hp! I have a ram air box on my Cuda. It cost about $150, but gives me about a 30 hp increase.