PHP:
In other words, in order to sound good, the installation will require installing additional horizontal 2x4's above and below where the speaker will go

If you do this to a conventional in-wall not knowing the T/S parameters for the woofer and you can seriously effect the low FS
of the speaker. That is why I recommended the above for use with infinite
Baffle designed in-wall speakers These are BIC in-wall's and while I think they
are decent they are still entry level in-wall speakers. I use them and install them in entry level HT's They are a good bang for the buck product.