It's possible download only the update 2 from insider app?

[fabiohvsilva]

And i want to know if the GDR2 its stayble on Lumia 830.

 

[ven07]

Nope..

 

[Harrie-S]

But if you want to try it.
Windows Insider app delivers Windows Phone 8.1 Update 2 to any handset which does not support W10M TP [Update: Here's how to get WP8.1 Update 2 on any device without going for Windows 10 Technical Preview] - WMPoweruser
But be aware that you may end up with W10 as clearly stated in the article. So be prepared to use the Windows Software Recovery Tool or else don't try.

 

[ven07]

Harrie is right, I answered to quickly 50/50 shot lol