When my trunk is open you can really feel the bass compared when it’sclosed

[Breaker]

100% but I think it depends on the overall application and not just being in phase. Almost all the big 4th,5th,6th order builds have subs firing at each other

The distance from the subs to the hatch to the subs is directly cancelling in the bandwidth. The reflected wave is cancelling the original wave. Hence when he opens it the cancellation goes away. Move the subs 4-8 inches from the hatch and it will sound better.

 

[MattinMO]

The distance from the subs to the hatch to the subs is directly cancelling in the bandwidth. The reflected wave is cancelling the original wave. Hence when he opens it the cancellation goes away. Move the subs 4-8 inches from the hatch and it will sound better.

See my first reply...

 

[shredder2]

This was my thought as well, though this will perform like a 4th order so results will be unpredictable. The issue I see is how far forward from the rear hatch the subs are. That's usually a recipe for cancellation and some nulls.

The subs ae pretty far forward that's true but anything will be an improvement to having them in a beauty-queen, halfazz 4th/sealed setup in the center of the vehicle like he has now.

I cringe just looking at it.

 

[MattinMO]

I'll illustrate what I said above. The 1st pic is basically what you have now without the hard floor as drawn.

I bet as long as the subs are in phase changing it to this will make a marked improvement as long as there's some space to the tailgate.

I'd make sure it has a solid floor and back wall along with changing it to what's shown (or close) if it was me.

Give it a try... its only wood.

Even though op hasn't been on/replied I really hope he tries out @shredder2 advice. definitely interested to see what the outcome would be. And if he does def needs to make a video.