I think it'd behoove you to go smaller on the rear chamber instead of 1:1, as in that alignment (and if that sub is similar to a zv4) you don't need 4cf on the rear..
I would start with 4cf gross, and make your rear port 3.450" tall, by 18" wide. Before you say that's too much port area, I do that so I can shove 4x4's in the port as a way to fine tune port area. You'll probably end up with 7-10"sq of port area if your using RMS power or higher.
If you listen to common bass-heavy music, I'd tune no higher than 28hz. Now, that's a long port...But. if you have the port exit on a common wall, it can effectively lengthen your port with no additional displacement. I always have good luck with my front port 90° out from my rear.
And forget all this tune-one-octave-apart BS, you need to have the adjustability to change tuning for your best in-vehicle response.
Front box wise, try to go 5.5-6cf gross, with 130" of port area to start, with the ability to reduce it. I'd tune it to 65hz, and reduce area and increase length as needed....Make it modular, with a slot port as a internal loading wall, if the sub and rear port are on the same plane.
What vehicle? I find, even if you have a dip in, say, 40-55hz, that cabin gain and a sprinkle of EQ can pick up that dip, and give you much better response and musicality. I'd guess you'd end up with 80-100" of port area up front eventually.
Right now I have 1 AQ HDC3-18 recieving 400-ish clamped watts in a series 6th in my Tundra, and it does 148.1 @26hz, [email protected]
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, and plays up to it's cross at 60hz mighty well. It'd play higher, but my "modular" box is poorly braced and resonates awfully bad from 60hz and up.
Good luck. JMO, btw.
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