Conclusion: I had to replace some blown Nokia speakers. The remaining Nokias sounded tinny. The addition of these two in the back gives depth and clarity to the music. Now, I can hear the locations of the individual instruments. Plan to buy another pair to replace the remaining nokias.
Summary: The Polk db501 speakers look and sound beautiful. They really improved the overall audio characteristics, especially by cleaning up the mid notes and reducing the "tinniness" of the stock tweeters. Unexpectedly, they were not an exact fit for my Lexus LS400 even though they were listed as such - the screw slots weren't long enough. However, by clipping off the end of each slot, they fit perfectly, and now I couldn't be happier with them.
Pros: Excellent sound, excellent looks and worth every penny
Summary: The gentlemen that helped me out, only thing is that the speakers were to small and the harness that was given with it did not clip in with the OEM harness. It seemed like he was so sure and trusted the team that did the fitment test for the rear speaker size for my subaru wagon cause I asked him if he was sure. it was so small i could fit the speaker all the way through the speaker housing.
Summary: Got these for my husband for Christmas for his beloved '91 4-Runner. He installed 4 speakers and a JVC stereo in about 2 hours. My product advisor at Crutchfield was excellent. I would have to say my experience with Crutchfield was the best on-line experience I've ever had.