my car is primarily SPL but i listen to rock/metal/punk so im working on making it sound better i have 5.25" comp set in the front and am wondering how to approach the rear to get more mid bass in the car, my car comes with 4 6x9's one in each door i made plates for the 5.25 in the front doors and am wondering if the 6x9 mid bass drivers are any good or if i should go with a standard 6.5"?

thanks guys