You won't get 32 Hz tuning if the port is inside the box because the port will displace ~.1 cubes. With the port you're planning to use, that will make your tuning roughly 36, which isn't too bad really, because you'll never get good low end response from that small a volume with a 12. I modeled a Type R 12 in that box and the peak will be in the low 50s. The -3dB down point will be ~33Hz.i actualy did a little research and found out my port legnth i didnt put the dimensions on my box but it will work it is a Ford F-150 Supercrew Cab 01-03 Dual Subwoofer Box and at 3" port at 32hz the tube would have to be 16.41 inches the box itself is rather long