midbass speakers

I looking for Some Cheaper (new or Used) Mid-bass Speakers for my next project. I'd like to play around with some different large Mid-bass Drivers for a Door panel install and not spend too much until i've heard some EXamples of the benefit of over sized Mid-bass door speakers. NO SUBS Only...

I was driving my girlfriends Kia Soul the other day and noticed how good the midbass was and I cant figure out why her car with a stock system has so much better midbass than my truck which has focal access components on a polk pa660. Obviously I don't have top of the line stuff but I would...