http://wccftech.com/download-ios-11-final-ipsw/

You can now download iOS 11 full and final IPSW update for all compatible iPhone, iPad and iPod touch devices. We have the complete changelog of the update in one place too.

If you’ve been waiting for the final version of iOS 11 to arrive, then today’s your lucky day. Apple’s latest and greatest operating system for the iPhone, iPad and iPod touch has arrived and anyone with a compatible device can go ahead and install it right away without much trouble at all. We have the direct download links to the complete IPSW file, and you can grab the update over the air too.