Update to custom IOS Firmware with unsigned IOS Version?

Ruffy98

hi guys,
3 hours ago, i successfully downgraded my Iphone 4s from ios 9.0.2 to IOS 6.1.3.
But now...i want to upgrade to IOS 8.4
Is there any tool that i can upgrade to this Firmware ?
because apple stopped singning this...

Gautam

Unfortunately, it is not possible to upgrade or downgrade to iOS 8.4 as the ability to create custom IPSW is not available.

Ruffy98

hmm...but over my iphone with OTA i can upgrade to IOS 8.4.1
Is there now a FULL Jailbreak possible ?
i mean, in ios 9 there is a full jailbreak too and not a particle