No stock Android for G900H?

I recently took this device from my sister and I am running a TouchWiz custom ROM on it which is not too bad but it is slow and laggy most of the time. I know how to manage the memory of an Android device since I have been using HTC devices forever now, but for some reason the TouchWiz interface is just really heavy and not as smooth and snappy as stock Android or HTC Sense, for example. I went to the Galaxy S5 Original Android Development section but I couldn't find any stock Android (AOSP, GPE, etc.) for my device (G900H) because all of them are for the Qualcomm based ones (klte); does anyone know if any stock one actually exists? It's just weird that there are many TouchWiz custom ROMs for it but no stock Android ROMs.

Thanks for your time, guys.

samsung galaxy s5 g900h after modifying problem .

i modified the default_gain.conf for g900h to increase the volume , it worked but while having a call and after accepting it m the phone will freeze and the other person wont be able to hear my voice .
can anyone help me with this problem ?