I've got mildly modded '79 Strat. One thing I'd like to do is improve the sustain. I'm contemplating getting a Callaham tremelo block assembly.
Last night I put on a set of steel saddles borrowed from a Robert Cray model.
One thing I hadn't expected was the tone to change The clean sounds good and maybe even a little brighter and louder but the distorted sounds a little more
'fuzzier" than I'd like it. I may put the original cast units back on but I'll give the strings a chance to break in and see how they mature.

Anyone have experience with this?
i would highly recomend getting the full callaham upgrade with block and saddles. i smashed them on my 2004 Am Std strat and sustain, tone, playability was increased and the treble strings stood out more (before they were thoroughly getting lost in the mix) making chords really play out nicely.

yeh i now swear by that mod and tell everyone to do it (and they dont listen. idiots. ahaha).

i havent snapped a string in god knows how long, and they stay in tune for longer than before.
steel vibrates quicker, making your highs jump out slightly more. the increased fuzz mgiht be due to that, or it might be psychological.
fight the power that be
I've played the guitar quite a bit and the strings have mellowed some, softening the tone. They also seem to be losing that "fuzzy almost muddy" tone with distortion, which was what I was hoping for.