Subwoofers and cab airspace?

A single cab truck would not have as good of lows as a 4 door right? Why does subs sound better outside the vehicle with a 4 door vs a single cab. When I hear ppl go by it usually sounds better the bigger the cab on their truck. Can somebody explain how subs sound in different cabs like single extended and supercrew cabs. I got two sq hds310's in big 35hz box on 2k @ .5 and inside the cab it sounds great and outside the cab its hard to hear it unless you are inside. Where as when I hear ppl go by with a 4 door they could have kicker or qpowers and outside the truck it sounds great but inside the truck it's not very loud.

I'm wondering how are my the sound of my subs gunna change coming out of my single cab dodge and into a 4 door ford. With a lot more cabin space will it give them a cleaner better sound or need more power with more cab space

Just explain how a certain pair of subs will sound in different sized cabs or interiors. Single cab vs a 4 door supercrew cab

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