resonance frequency

[er1kkull]

Ive been reading to get ur box to sound best(sq) or best spl (Cant remember which one) that i need the resonance frequency of my vehicle (02 chevy s-10) and to put it in some type of match with the box frequency. is this true if so how could i find the frequency of my truck or maybe someone already has it? i searched for it on this forum but cant find anything close to the subject. Also i was wondering if it would be possible to have a box so when u hit a switch a actuator(they cost a good bit) pushes out and pulls in a wall to close off the ports?
thanks

[mattj]

make sure you are 1/4 waved at the microphone point and that you know that exact frequency which is what you tune your port to. get this by dividing dividing the speed of sound by 12 ( 13560)and then divide that by the # of inches from the dash. now take that # and divide by 4.... you now have your 1/4 wave freq. tune your box at that.

oh and its for SPL...