You do realize that from 141 to 152 is a really huge jump. As you get up into high 140's you will very likely no longer gain 3db for doubling power and/or cone area. A friend of mine does @ 150 out of a trunk civic with 5K and a single 15 (db drag style sealed), he has done 52 and change with 10K but subs don't survive.... really subs don't survive 5K for long. His box is very solid and he has a lot of work into it.
If you want to break 150 you should also buy an SPL meter, some woodworking tools, and lumber. I don't believe that new subs are going to be the magic answer that will fix either your getting that much louder, or being able to play 25hz properly.