I purchased a used BMW-Z3 a couple of months ago and was looking for a good 5 1/4" speaker to go into the kick pannels as I was unhappy with the very hollow/midrange sound of the existing speakers. I wanted something that would provide more bass as the car has a small midrange and tweeter in each door. I installed the speakers this weekend in probably less than an hour, both dropped right in the facory speaker mounting holes and bolted right in. I was also surprised that I didn't need to change ANY of my connectors on the factory wiring harness as the factory speaker wire plugs mated right up to the terminals on the MBQuarts speakers. No you're not going to get the bass that you would running a sub, but these speakers can REALLY handle some power as I tested them before I put the pannels back in. I could crank the aftermarket Sony head unit all the way up, bass response was MUCH more notice able, but I could tell these could handle MUCH MORE power as the woofer was barely moving. The ONLY distortion I got was from the power amp in the Sony Head Unit. So now I'm back here looking for a power amp. I'd reccomend these for replacing ANY 5 1/4" car speakers, so far they've been great, I just need a little more power to push them so I can hear them better when the top is down in Atlanta traffic. I gave them rating of 9s and 10s as I was only able to hear Infinitys in the local stores, my other option would have been the JL Audios, but I'm VERY pleased with the MB Quartz for the money and FREE shipping was a BIG plus.