In wall sub for mid base ?

I am looking to add to my 5.2 HTS a two in wall mid base speakers(I am thinking 6 1/2 " or 8" driver) for more mid base punch,probably is going to be custom build,does anyone know is any company doing this ,thanks
You'd have to use an a additional crossover in the system, and take care to properly ajdust for phase, me thinks.
I think it's typically much much better to simply work on getting the speakers setup properly for good coupling at the crossover, and same for the subwoofer - proerly placed in relation to seating also, of course!
I would bet that, if your not satisfied with your midbass, it's probabaly a problem with you having your speakers, subs, and seats not properly positioned in relationship to the bass modes, phase, and crossover in the system. And you just might also have a problem with phase between multiple woofers, and might be experiencing some holes,phase issues, and suck-outs in your sound!
I'm recommending you check the balance of your system, ONE SPEAKER AT A TIME, from the seating location(s).
But, yes. If you are trying to do some more involved system, adding small woofers for upper/mid bass and such, then you will likely be getting an adjustable crossover in the system. That, my friends, is a bit tricky. It also can be screwed up a lot more easily than and it is to pull it off with excellent results!
To consider...