Glad it worked out for ya. Also, very nice job on the writeup with super clear pics - I know I wouldn't be able to do as good a job in your native language - no apologies necessary for your English! It's better than the posts I see from some guys who grew up here!!
Modifications such as this just don't float my boat, though. I guess I just really dislike cutting things that don't really need to be. I'd rather pull the sub out as per normal procedure and not cut anything. I did re-foam my original ML and it's still in there kicking away. It's good enough for me as I'm definitely not an audiophile.

 

Thank you very much, Campisi!

100% agree with you in cutting things, if there's a 2nd way.

I was only afraid to break something, or any parts would not fit perfect again
(a noise making or so)

I had Brax amps and front speakers in my last car,
but times changed, and the ML is quite good for a original system with this age