Kicker and JL make a 6.5 inch sub (even though people will say it's a mid range speaker.. It's a sub)... Thats the dilemma I'm in now as to whether they will fit in the space provided right behind the seats where the subs go. I'm going to take the plunge and order them(I'm going with JL) tomorrow and hopefully will get some info out there as to size, sound, etc. and if they fit some, take some pics/video of the installation... I changed everything as well in my SRT-6 and wow.... definitely huge difference in sound... I have Kenwood in dash with DVD/Nav system, Aline Components with an Alpine 4 channel amp.... If the subs don't fit in the space behind the seat I'm going to buy another set of components and place the mid range speakers where the subs go. Maybe install the tweeters in the dash or if not in a space right behind and between the seat and safety belts and then I'm going with any slim line sub and small but powerful amp... JL, Kicker, Pioneer, Rockford and Kenwood all are making very slim amps and subs to put almost anywhere. Hopefully I'll have more detail and info on my sound system.