Since I gathered much of the information I applied towards upgrading my 2004 MIM Fender Jazz bass from these forums, I thought that I would share my experiences here. Last year I made the move from guitar to bass and purchased a used, wine red 2004 MIM Fender Jazz bass that was completely stock and in like-new condition for $350. It even still had the protective plastic on the pickguard. Following a good setup by my hands, I enjoyed the bass right from the start, but quickly embarked on an adventure to make some changes for a few reasons: 1) I enjoy working on things; 2) Some things, like the bridge, just didn't work well; and 3) I couldn't achieve some the tone and flexibility I knew was possible from a Jazz bass. So, I'm going to share what I did in the order I did it and my assessment of each upgrade's overall effect. 1 - New strings. Off came the Fender round wound strings and on went a few different sets of flatwounds. I tried the Fender flats (9050ML), but I found them too dull. Next was a set of D'Addario chromes, but they were too bright. I settled on the standard Ernie Ball flats (Group III), which, like a good bed or bowl of porridge, were just right. Effect: Immediately noticeable and wonderful. A big step towards the sound I was looking for. 2 - Replaced the bridge with a Fender vintage-style bridge with threaded barrels. I read the discussions regarding high-mass versus bent metal bridges and decided I really was after a vintage tone, plus my issue with the bridge wasn't its sound. The problem was the stock bridge height adjustment screws would not stay in place without Loctite and the string alignment over the pickup poles was poor. Both issues were solved with the vintage-style bridge at a reasonable cost. Effect: None in tone, but allowed for a more solid and consistent setup. 3 - Replaced the pots and caps higher quality components (CTS) with the same rating values. This was perhaps a bit of phantom chasing, but I was disappointed with how little range I had in adjusting the volume of each pickup and how little the tone changed when favoring one pickup over the other. I mean, where was all the versatility I bought a Jazz bass for? Unfortunately, despite the fun I had with a soldering iron and the knowledge I gained of the bass's circuitry, my changes had no effect. Effect: Absolutely none. 4 - Shielding - What's to say? I applied self-adhesive copper shielding to the pickup and control cavities. Effect: Noticeably less noise. 5 - New pickups. Merry Christmas to me! After having the bass for just over a year I got a set of Seymour Duncan SJB-1 pickups for Christmas and the bass finally had the versatility I was after. The Duncans have significantly more punch and richness than the stock pickups. Plus, now there is a very clear difference when favoring the neck or bridge pickup. On top of that there is a more usable range in both volume and tone pots. Effect: Dramatic. 6 - New tuning machines. Along with the pickups I got a set of HipShot tuners for Christmas. The stock tuners did a fair job of holding tune, but were sometimes finicky while tuning and seemed to "jump" and force me to chase the tuning needle. The HipShots are rock solid and easier to dial in. Effect: Minimal. I could have easily lived with the stock tuning machines. The final episode was not really an upgrade to the bass, but was a new amp. I replaced a little Fender Rumble 15 I was using for practice and a Behringer BXL-3000 I was using for performances with an Ampeg PF-350 with a PF-210HE cab. Yowza! Shazam! The whole package is absolutely dialed-in for tone I love with the flexibility to adjust that tone given the specific style of music I'm playing. For the first time in a year I am living completely G.A.S. free. Excluding the amp, the upgrades I made didn't really cost that much: Strings: $25 Bridge: $24 Pots & Cap: $21 Shielding: $16 Pickups: $115 Tuners: $100 TOTAL: $301 Like I said, I could have gone without the pots and tuners and still have the same end results, so I could have gotten where I'm at for $180 ($155 is you exclude strings, because they are essentially consumable). I've played American-made Jazz basses that cost twice what my "upgraded" bass costs and I don't think anyone could discern the sonic difference. Good or bad setup will affect the playability regardless of where the bass is made. So, at this point the clear differences are cosmetic and weight - the finish and visible wood grain on the American Fenders are beautiful and they are noticeably lighter. And, of course, the resale value of the American Fenders will always be higher. But, I didn't do this with a goal to recoup my costs by selling an "upgraded bass". I wanted to take my moderately-priced used bass and extract the best tone I could get out of it. I've actually kept all the stock parts, so could return it to original condition if I want and use the upgraded bits to build my own bass. But, I think it demonstrates that you can make some reasonably priced upgrades to a good condition, less expensive bass and end up with some darn fine results.