I recently swapped my fender medium-light strings with a heavier set of ernie ball power slinkys (110,90,75,55). I've had to adjust the truss to compensate for the extra tension which I'm reasonable happy with. My action still seemed a little high so I've lowered my bridges. Whats bugging me is the intonation, my fretted 12th notes are sharper than the open note (some guides say use the harmonic 12th?) so I moved the saddles back a bit but it doesn't seem to be making any noticable difference so I left it alone because I've got a feeling something else is wrong. How far back should they need to go? I'm thinking only a few mm. Is a bog standard ga1 tuner good enough? Another thing I've noticed is that I sometimes get a slight buzzy noise coming from the bridge/saddles. Could it be that the strings are too big to sit on the saddle correctly and thats also why I'm struggling to get an accurate intonation tuning? Aaaarrgghhh!