TWQT Response calculation

[j3price]

Hi All ,
I am currently contemplating my next loudspeaker project, The Fist was also documented on this forum (Bass Reflex Fane sovereign Beyma Cd10FE).
The main downfall of my first project was the lack of bass; I have looked into producing a sub …. Tham6, 10 or 12 (could not decide they all look great) but multiple amplifiers adds complication and additional expense.
Would a Tapered Quarter Wave Tube be the solution? From my understanding I would be able to produce high quality bass from a driver with relatively high FS and or low Qes, qts.
This design by Ingvar Ahlberg looks to for fill my brief. So my questions are what kind of bass extension can this achieve.. I have Horn resp but not sure of how to simulate TQWT, my understanding is that physics are complicated. The other question is the position of the driver relative to the Tube, Can I afford to move it a 30mm down to accommodate my horn fare 145 x 145 .
Driver possibilities:
Beyma 12P80Fe (cannot afford ND)
Beyma 12G40
Or adapting the design for the Fane Sovereign 10”- 275w
I have many more questions but don’t want to write an essay  !
Thanks,
Jerome