Exactly my point to audioholic. The resonant frequency is definitely where you'll be your loudest, but few vehicles are loose enough to peak below 40hz where you're going to do your hairtricks. Look at hairtrick vids on youtube. They are usually someone who knows what they are doing and has done some deadening. This raises the Resonant frequencies and moves the peak AWAY from where the hair trick will be done at. They have compensated for this with their box tuning. I can't really remember of anyone stating they had a resonant freq of less than 40hz.