I'm going to build a box for a buddy of mine that has a 1988 Camaro Iroc-Z. It's not going to be in the wheel weld as of other boxes. But right behind the rear seats. In this picture where the amp is located, there will be an enclosure for them, and it won't cover up the whole trunk area. I am going to use dual 4" Areo ports, and I was wondering how long will they have to be to have a tuning of 32-32hz. I'm thinking 1.6-8 cubes in total for both subs, and the amp I am using is a Polk Audio 4channel 800 watt amp that will be bridged to run at 4 ohms. The aim is mostly for SPL since there is no true SQ. But he would like to be able to listen to a variety of music, such as: rock, rap, alternative, just about any random think you can think of. not really.. His system as of right now is running an Alpine CDA-9884 running Infinity 4x6 fronts, and pioneer 6x9, and will be removing the extra set of 6x9 running off the amp. Just a little help, if you can. Thanks SSA!