Like the original post here, I too embarked on the same journey with Sound Innovations and opted for the entire front stage replacement with Focal speakers, including the front footwells and rear deck replacements with 8" Focal Woofers. All I can say is WOW. What a dramatic impact this made to the staging and low end output.
I have had many high end audio systems in the past (factory optioned) such as Bang and Olufsen, B & W etc and I can say unequivocally this upgraded system blows them all away.
I actually would have been happy just matching the last B&O system I had, however this system comfortably outperforms it in vocal clarity and low end bass . While I contemplated a sub woofer, I felt that I wanted to keep things stock and actually prefer clean bass anyway, rather than heavy bass that some subwoofers provide.
The drivers were matched with Mosconi Class D amplifiers and provide more than enough power to drive these incredible speakers. I cannot compliment the Sound Innovations team enough. They took their time on every little detail, even fabricating mounting brackets no-one will ever see and etching LUCID into them. Attention to detail that is very rare these days.
So whats next....
Well, I am so happy with the front staging I think I will save up for phase 2 and do the same treatment on the rear staging to complete the build.