Hi There, Strats have kept what I call a "Basic" tone and the difference comes with the fitting of non fender pick ups of which there are a host of. Fender tradionally used and still use Single coil pick ups. Different voicing was made via pot values 1m-250 ohm. and capacitors and resistors. Here are a couple of sites ref Strat pu's.
http://www.legendarytones.com/vinpicup1.html
http://www.areyouexperienced.net/
fender_custom_65_pickups.html
http://www.vintagevibeguitars.com/windows/
sc_90Win.html
http://www.specialtyguitars.com/fender/pickups.html
Fenderphil