I only see the JL TW3 series and the TW5v2, I don't see anyone seeing a TW5.
But that circles back to the original question in essence: does 1 sub like that give better results than if I maybe pick up 2 DD SL600 10s that are happy in a .75 ft3 ported box, which would be 1.5 ft3 for 2 in one I think.
Depends. Alot of the time running 2 subs instead of 1 can lead to less than ideal airspace. This often times cuts down on low end response and makes the box naturally peak at a higher frequency.
But 2 subs have more cone area and will naturally have more ability to move air at lower frequencies.
Assuming the fs of the 2 subs is fairly low and the box is close to optimal I'm gonna say that it will be louder and likely cove the same frequency range better.
But if the box is much too small you will lose bottom end. This is where modeling software comes into play especially if you can model in you vehicles cabin gain
Cabin gain is what makes sealed boxes work since sealed boxes usually **** below 40hz. Luckily cabin gain below 40hz usually helps flatten the response.
Looking back at the post I do not believe that the sl610 will be happy in .75cube ported box, you will likely need at least 1 cube if not 1.25 to perform optimally
