In total this build is much better imo. You still dealing massive damage and can deal with tanky champions much better. The ability to have endless mana and high life steal on Sivir is awesome. Every losing matchup becomes winnable
Navori let you proc more skills. More skills - more W cast. More W cast - higher attack speed(Ult passive) and insane splash damage. Higher attack speed - faster Navori proc :D

Im sorry if I did something inconvenient for you guys, this is my first guide x-x Im not so familiar with the site and all the features here. My idea behind this build is to return Sivir back to life. Her personality got gutted by Samira. Her kit got stolen and improved by Akshan. But we still have our queen which IS viable and WILL dominate Summoner's Rift

P.S. I remade this guide being logged-in my account, fixed mistakes etc. If you like it, Ill try to improve it every patch and look for somehting interesting. Maybe till that time Ill get used to the site and make this guide more appealing ^^
Hope you will have fun with this! Good luck!