Well, when I got this guitar, just the design of the bridge the action would only go so low so I originally shimmed it to get it closer to the strings to make the action a little bit lower but also the neck angle will determine if you need to shim the neck or not. I basically have the action adjustment as low as it could possibly go and the neck was perfectly straight The action at the12th fret was higher than it was at nut which is normal but in this case it was extreme, so I shim the neck to make the neck angle a little bit flatter and parallel with the body to make the action more consistent across the whole fret board obvioust the action will always be close to the frets at the but then it is at the 12th fret but it was way to much of a differance in this case . Stew mac sells diff degree angled shims or in a pinch you can use sand paper ud be suprised how much 1-2 mm make a differance .