Re: Anyone running 7" or 8" inch Midbass in door
it has nothing to do with volume and everything to do with frequency response. By having a midbass speaker that can play low, you can improve imaging by bringing the bass to the front of the car, add the snap and punch midbass frequencies that so many systems are lacking, as well as clear up your midrange by taking the strain off of it.
What speaker you pick is really just a function of the design characteristics of the speaker itself, not just the size. For instance I have a 15" sub - but I am not a basshead and have less bass than most people's system because of the way it is tuned. I use the larger speaker because it was the best choice for filling in specifically and only the deepest frequencies (50hz and down).
In general an 8" will help a little better with the lower 50-60hz frequencies, but it just comes down to which one meets your needs and will work well with your other drivers. A lot of midbass speakers would not work well for me because they would not play high enough to meet the fairly high crossover point of my 4" midrange driver.
Phoenix Gold used to make a 9" slim mount midbass speaker as part of their Titanium Elite set made by Morel. I haven't read many revies of the midbass itself, but I've heard a lot of great things about the Titanium Elite series in general - as I would expect of anything made by Morel.