xperia z1 firmware :
for download android 5.1.1 for xperia z1 click her
for download android 5.0.2 for xperia z1 click her
for download android 4.4.4 for xperia z1 click her
after you download the firmware change .rar or .zip to .ftf
xperia z1 flashtool :
download flashtool for windows click
her