This thread was prompted by the setup and tweaking of the three Precision basses I've owned over the last 8 or so years since I got my first P and the difference those small tweaks make. My first P was an American Vintage 1988 '57 Reissue. One of the first modifications I did was to replace the anodised guard with a tort one. Not long after this I crossed paths with another P player with an anodised aluminium guard. He insisted that the guard changed the sound of the bass but I was sceptical at the time though... A few years later I decided to put together my 'dream bass', a vintage Lake Placid Blue Precision out of parts! The first thing I bought was an awesome '66 neck with good frets. Because I couldn't wait until the bass was finished, I decided to bolt the neck to my '57 reissue just to get a bit of playing on it. This was my first experience at HOW MUCH difference a single change could make. The '57 instantly sounded so much warmer and sweeter. I couldn't stop playing it for a couple of weeks. I gradually accrued the other parts for my buildup. A nice light '72 body, Lindy Fralin pickup, badass bridge. I put it together, but it sounded a bit dull and muddy. The first change I did was to shim the neck. This meant raising the saddles on the bridge, increasing the angle of the strings on the saddles. It instantly became more resonant and punchy, with better clarity and definition. I played it like this for a couple of years but always felt it looked a bit odd, with the Badass almost hanging off the back of the body. I did a bit of research and discovered that in '72 & '73 Fender placed the bridge around 5/8" further back on the body. I decided to move the bridge to the original 60's position primarily for appearance, but it also dramatically improved clarity and definition as a result of a tighter string angle on the bridge. I also installed a Volume and Tone bypass which is almost like a bright switch (for when you need a metallic clang). But back to my '57 reissue. I pulled it of retirement recently and reinstalled the aluminium pickguard. And yes, the aluminium guard DOES sound different to a tort one!