I just came up with an idea of porting one of my 15's. I saw a set-up that i really liked. it's probably gonna go in my bro's civic so there's a lot of room in there. but the main question is, what tuned freq should i tune the box to? i like deep bass, and i mean deep, with a little bit of pressure pushin my back. I keep on hearing that 29 htz is good for this. u peoples out there know? also, i wanna put in (2) three inch port tubes. would i just consider the diameter and the length of both the ports when calculating? thanks.