I got a new Fender Mexican Strat Saturday and bought some 9-42 supper bullets. I just put the new strings on and it seems like it's badly out of tune even though my tuner says it's fine. Also when I hold down some of the lower frets the strings will rattle against the frets. This happens even worse when I palm mute. Help?
It could be the intonation that's off. Adjust the truss rod or take the guitar to a shop that can do it. The fret buzz might be because the action is too low - adjust that too.
it sounds like you put the strings in the wrong spot
sounds like the strat came with heavier strings stock so now the neck has less tension and is bending, thus causing the buzz. You just need a neck adjustment, and possibly a saddle adjustment to go with that(which would explain your intonation problems).