Thanks for all the responses, I appreciate all the input. As much as I agree with all the input I have a slightly jaded perspective since I have been trying out the theory for last few months. I installed the AP NZ3s in the dash last year along with a pair of JL 10W0s, additionally I put a pair of Tymphany LAT 300s that I had laying around below the sub box in a very poorly sealed box. Other than the LAT drivers getting to excursion limits when I beat on it, I have been happy with the overall frequency spectrum layout and have not had any major "pulling" to the rear. I have just been itching for more midbass since the LAT drivers are just a bit weak. I am running the NZ3s down to 320HZ with now issues, so I have not been hearing any vocals behind me.
Now I am more than happy to admit that I am no expert, so maybe a more focused ear would pick up rear vocals. I think I am going to move forward with the plan and in the end I can always add midbass forward and keep all 4 woofers as sub stage only, in the end this whole hobby is just one big experent isn't it.
I am considering running these drivers due to the small space requirement, any thoughts.
https://www.parts-express.com/morel-...oofer--297-066