Factory Reset Which iOS

[Photogdave]

I have a 6s Plus on iOS 10.3.3
Every now and again....maybe once a year I like to just wipe my phone...setup as new device and start from scratch. I always find that when i start feeling like its sluggish or buggy and I need a new phone, this cures it.
Recently I saw a speed test with the 7Plus and 8Plus. I decided to do the same test opening those various Apps in sync with them, and was astonished at how many my phone opened faster than both the 7 and 8.
And now worried about updating to iOS11 and slowing my phone down.
So my question for those who know...If i factory reset my phone, will it come back with iOS11 or where I left off or what it originally came with?

 

[Strelok]

I believe it will go to iOS 11, but there is still time to go back to 10.3.3. I believe Apple is still signing it.

 

[Photogdave]

Damn. I guess I need to hurry. How do you go back?

 

[Strelok]

I would google it to make sure, but from what I remember: get the ISPW file for your device, put into DFU mode and connect to PC/Mac, press shift + click on upgrade/update and choose that ISPW file.

 

[Photogdave]

Will do