Hello, everyone. I'm a newbie on this forum.

I'm considering trying IB in my Lexus LS430.
3-way SQ setup. At the moment the sub is Sinfoni C320 in a sealed box, but it has to be rebuilt to fit correctly and to direct the sub upwards.
Love the sound, a very fast, deep response. But it will take a lot of work to rebuild the box.

I've attached the photos on my trunk. The rear seats do not fall down, there's a refrigerator and there's rear AC system. + there's a sound insulation behind the seats and I installed.

So the only way the air from the sub is coming - is throughout the factory 8 (increased to 10) inch hole in the rear deck.

I wanted to try 1x15 or 1x18 FI ib318 v2 pointing to the trunk so the air will come throughout the rear deck. (4-th picture attached).
Reasons:
- Easier to build the baffle than to build a custom sealed box.
- Takes less space / less weight.
- To play very low with ease.

Can you please advice - is it worth it to build an IB in this trunk and the best way to do it?
Will the 18-inch sub match the speed of my 6 inch midbass?

Thank you very much!