I'm having a 3 way eclipse speaker setup installed in the car, and I'd like to put my subwoofer in the car too, JL 10w7. Should I put it in the trunk or behind the front seats. I'd like it in the trunk out of sight, but not sure how bass transfer will handle between the wall (where the convertable top folds down). Any opinions? And if you don't like subwoofers and have neg comments, please post elsewhere, I'm not looking to put multiple subs in, just 1 10" with a JL 500.1 amp.

Where you put it depends on how much BUMP you want.
If you put it in the trunk when you put the top down you may only hear it when you are stopped. You should still feel it though.

If you put it in the cabin the bass and bump will be better but you will be amazed at the difference with the top up and down.
With the top down you will lose about 10 to 20 db of bass.
My experience is with a 107 not your 129 but either way there is a lot
in the way between the trunk and the cabin.

If you search for my posts in the SL forum you can see what I did to mine. Even after all I did when I put the top down the difference is amazing.

Looking at your speaker/amp combo you have made a good match.
I wonder what kind of box you are going to use.
That will also affect the Bump vs Bass.
I wanted to do a ported box but I did not have the room to port 2 10's.

Hope this helps