For several weeks we have seen hints and shadows of Android 4.3 on various devices, but now we have an actual leaked download that is designed for the Snapdragon-powered Galaxy S4 (GT-I9505). The folks at Sam Mobile just this morning shared the leaked download of Android 4.3 for this version of the SGS4. The port comes from the Google Play Edition Galaxy S4 (GT-I9505G). Here's a quote below with the details,

Android 4.3 port from the Google Play Edition Galaxy S4 is fully functional on the standard Snapdragon-powered Galaxy S4 (GT-I9505), there is not even a single thing which isnít working. We havenít made any changes to the port, so itís 100% original with zero changes.

Note:
- This is not flashable through Odin.
- This will void your warranty.
- Donít attempt this if you donít have the skills to flash a custom ROM
- You are doing this on your own risk

System details:
Android version: 4.3
Build ID: JWR66N
PDA: I9505GUEUBMFP
CSC: I9505GXARBMFP
Build Date: 26 June 2013
Changelist: 968842

Requirements:
- Samsung Galaxy S4 (GT-I9505)
- Custom Recovery

Instructions:
- Copy Google Play Edition ROM to your internal SD Card
- Enter Recovery (Power + Volume Up + Home)
- Do a Wipe/Factory Reset (Necessary due to new Android version)
- Flash Google Play Edition ROM
- Reboot your device!

Download: (Choose either one)
- Android-4.3-I9505GUEUBMFP-Odexed-I9505.zip
MD5: 363ED9CC32A841A512E72372A19C7D05

- Android-4.3-I9505GUEUBMFP-Deodexed-I9505.zip
MD5: 74D241B64266220161018EB98A19F279
Feel free to do a happy dance now.

Source: SamMobile