Re: 07 lucerne + 2 type R's
i've built probably over 40 boxes for the 12" type R. the box will perform if it is bigger. 2 cubes per sub if running lots of power (like a 1000rms or more) and 2.5 cubes if running less power. tune it to 34Hz. use a single 4" flared port per sub. on paper this isn't enough surface area but the type R's like it this way. for the two speakers you could also run a single 6"-- more expensive but generally a 6" outperforms 2x 4".
4x 12" HDC3's
1x Hifonics Maxximus (rated 10,000@1ohm)
2x Powermaster D3100
8x runs of 0 gauge
1x stock alt
155.2 dB legal (vehicle off and @50Hz) in a Ford exploder