The GS carts are PG, not VG. I have a GS kit, but was soon much happier with a 510 system. I tried adding VG juices to the GS carts, but it just didn't work well. No matter how I added the juice, the carto became either clogged or gurgly. And the GS passthru I got burned the juices I added.
I also didn't really get huge vapor from thhe GS even with stock carts. It was ok, but the 510 was way better. So I came away thinking all those vids were to make us think we were getting big vapor when we weren't. It was certainly not a "vapor monster", although the PT with stock carts was pretty good...at 5V it should be. The batts didn't keep charge after a while, but I had it more than the warranty period, so was screwed.
That said, the batts are "E9" batts, and there are other E9 models. There may be a vendor that sells VG E9 cartos...and probably would be cheaper than GS's expensive prices. Nhaler sells e9 stuff, so you might ask Drew (owner) if he can do VG.
I noticed that now GS is claiming one carto is equivalent to 2 packs of analogs. That would be 400 drags per carto! I think they are getting desperate. I hate to recommend this, but if PG is an issue for you (it is definitely for me) then returning the GS and getting another better model would be probably the best remedy. A quick goggle search for VG e9 cartos came up empty, I'm afraid. Good luck!