HELP NEEDED on enclosure design

[DerrickC9035]

Ok so to start off I'm New to the competitive audio scene and I just did a major upgrade on my vehicle and sound system I went from stock alternator and voltage 13.8 to the high output alternator and voltage of 15.8 running a 29AH SCIB bank from NORTHWEST LITHIUM anyway it took me over a year to get my power supply right now I have ordered a 15" Incriminator audio TYRANT rated for 5K RMS with a CAB-45 V2 it's currently in a D4S HD3 single 15 enclosure which does really well BUT!!! It will Not fit in my trunk and doesn't sound like it should in the current setup which is a Russian no wall type install I just joined a Team here in TN and my closest team mate is 2hrs away and doesn't know exactly how to do what I'm trying to achieve so I am trying to get into competing on a regular and will eventually buy another Tyrant 15 and run them in a 6th order but in the meantime while I'm learning I'm wanting to do a trunk build and put a second Cab-45 on each coil for the best possible results in the lanes for a total of 9k to the sub but I'm told that in order to not blow my sub I need to make the enclosure smaller than spec for cone control when putting more than the recommended rms rating to the sub does anyone have experience with this and if so can you please help me design an enclosure for this monster woofer the current box it's in the D4S HD3 single 15 enclosure is almost spec from what they told me at Incriminator audio (24HZ FS) and the sub works best in an enclosure around 4.0 cubic feet with approximately 80 inches of port area and I can tell on the CAB-45 in the Enclosure that the sub is reaching it max potential excursion wise so I definitely need the Enclosure smaller than the current one but how much smaller should it be and do i need to decrease the port area as well

[Joe X]

Post your vehicle model and maximum possible dimensions for a box (HxWxD) to see what kind of trunk space you have. Ideally you want the same 4 cubic feet that already worked for you or as close as possible.