I've just replced the stock speakers in my s2k. I've read about a lot of different brands of speakers and modifications necessary to put them in but I decided to go with speakers that would'nt require cutting the speaker basket or an amp. Just pop em in and go. I went with the eclipse 82641 speakers. Great sound and they pop right in. Compared them side by side with the Sony xsv 1621's and the xsv 1631's. Definitely better than the 1621's. About even with the 1631's. These are a great choice for those people that just the radio to sound good w/o going nuts. Available at Tweeters for $120.