Box tuning and port size help

[REDz28 10+ year member]

So been using my current throw togther in a day box, tuned to 34hz with bout 2.4 ish cubic feet. I hit 136-138 a lot and a couple times got 139 off some sweeps. This is off one 12" American Bass VFL Exterme. I found out today the resonance frequency of my car is 49hz and that's where I've been peaking I guess. This is on a 2002 Camaro, so hatchback. I'm thinking of doing sub up close to the port, then port facing rear. Tuned to 46hz? Need help figuring out where to tune this box. Also I'm thinking a 4" wide port. The box is roughly 11" high by 14" deep by 37" wide. With .75 thickness mdf. Would 4" be to wide for my port? Any further help is greatly aprretiated but I'm trying to break 140 tired of these 30s plus I see scores where guys have like 2 15"s only hitting 143 I'd like to show that 12" off to the world haha.

Thanks let me know

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[REDz28 10+ year member]

ive been told port forward sub up. now my problem with port facing forward is that my rear seats are directly in the way theres only about the top 3" directly open so i do a 3" port on the upper portion of the front side on my box?

 

[REDz28 10+ year member]

or would 2 3" flared ports do good? i need the box tuned around 46hz