If you have no problem with the airflow, then the PV GonG should be fine. I was under the impression reading your post, however that you had airflow issues until you mentioned otherwise. Your stock stem should work fine with your reducer for vaporbonging. I'm unclear as to whether you tried it or not. I prefer the PVHES FWIW (we are degrading into a society of acronyms, sadly). I also have the non-HES GonG at was happy with it, but the PVHES is better IMO.