I was actually going to ignore your post, because I found it somewhat offensive to PV but I can't any longer. Don't you think this research has already been completed (at a much more involved level)? PV has done all the testing already, so you may want to reconsider your statement that a full bore open single hole is the best. The reason you are getting poor hits with the notches, channels, etc. is because it has to be done properly. I don't know sweet jack about glass, but i'm pretty sure there are exact tolerances, etc. that need to be adhered to.
I've tried the single open full bore hole, and yes it is a bit better than stock, but not much. This is why PV is going to continue with only the 4 hole PVHES because a single big hole doesn't justify the cost to make it. I agree, having beta tested the single open bore, because the bottleneck in airflow isn't that. It's around the stem and the tight fit hinders airflow...and this is why the PVHES have both the notches AND the channels cut into the sides. You can disagree that it's better, but many are waiting in line for these, myself included because we trust PV, and know they will meet the claims of 30% better airflow, because many PVHES owners on here have already confirmed it.
I'll gladly throw my $$$ at PV and let them handle all the testing and manufacturing, since it's their gig.
IMO, if you place a SS screen in the bottom of the heating chamber you should solve the tight fit airflow entrance to the stem. Do you ever tried that?? If you want, you can even add a couple slits to the rim, or one at a time and test for airflow, the way I did it.
You wouldn't need any channels, slits on the rim or whatever. Look at the simplest glass stems being made by log manufacterers.
IMO, those channels only cool down the area in between the heating chamber and the glass stem, creating a faster cold air intake from the top of the Solo heating chamber, Tintest already explained this like 100 posts before, creating uneven vaped material at the top of the loading chamber of the stem... makes sense???
If you just manage & prevent the stem from touching the bottom of the heating chamber, you'll succeed and get like 30% more airflow(even with the stock 4 holed glass screen), like PV stated airflow...
After that SS modification, if you drill that glass screen you'll get the 100% more airflow, IMO.
Maybe at the first pull is less airflow, but after the air being compressed and heated in between the heating chamber and the glass stem, ASA enters the Solo stem chamber,
it escapes really fast through the full turbo bored stem
thus creating more airflow, makes sense??, it's like flasks bongs, after you fill them with vapor, is a piece of cake to get a massive huge rip
I hope this make sense and we don't fight
and argue.
BTW, all my mods been done to Arizer stock stems(4holes) and PV Solo stems and GonG stem adapters.
So I bought before from PV, if it's that the reason why you are upset with me.
I'm not trying to put down PV work, but I think it can be upgraded.
BTW, when I'm done with my own stems, I'll SEND YOU 1 FOR FREE, if you don't like it, you can criticize it or dislike it, but pass it on, maybe someone enjoy it !!!!
BTW, how do you know PV has done all research possible??? Do you work for them???
I already stated before in my posts that my own homemade mods upgraded airflow in more than a hundred percent IMO, yes more than a 100 %, so when PV states 30 % only, is like, what am I doing??
I really want to see what means, is properly done for you???
FYI all PV Solo stem GonG joints are the lowest quality I ever tried, all uneven cut and a pain in the butt at the moment of cleaning that huge vapor cloud from glass pieces, they always get stuck, making a simple task really complicated and clumsy when dealing with glass, water and electricity. Happened to me, unstucked suddenly making the Solo fly to the air
Have really sloppy welds and many huge imperfections.
IMO they are using the cheapest glass at hand available.
And considering the price, IMO, $20 bucks or more shipped to the US, I've seen A/Cs for almost that price coming from Canada as well, with a lot of work and much more beautiful than a plain cheap glass stem.
You can check smoketower.ca from your country, I'm not lying, I saw a beauty for $30 shipped free to the US, check our own "Cheap Quality Bubbler thread".
Those 4 warts to avoid them rolling when placed in a flat surface, IMO, a waste of time and glass and work, increasing the cost, IMO.
Use those 4 warts, and make them mini 4 warts but inside the stem, instead of a 4 hole glass screen.
Like ice pinches in a tube, to hold the SS screen in place, and easy to push the screen with a wood skewer when ready to be replaced or cleaned.
I swear I'll laugh so hard If I saw that modification in next PV stems,
lol
IMO that's the next step in Solo stems, customizable loading chamber by yourself
3 loading mode setups,
#1.... SS domed facing to the heating chamber, famous "shorty" stem
lol
cost in $$$$ cero, zero, 0,00000, niente, thanks,
what's the point of having a "Shorty and a Regular" when you can modify ONLY ONE STEM with a TWIST of a SS SCREEN?? (I'm pretty sure the Shorty PVHES works awesome, but...)
Answer, more money for PV pockets , is that hard to believe???
#2... SS flat, regular loading
#3... SS domed facing the Solo stem mouthpiece, extra loading chamber, for those that can't never get enough of a Solo
lol
I'm not a glass blower myself but, IMO this stems are really simple and you don't need to be a scientist to figure out airflow in a single stem.
I drill, clean, test,
cut, clean, test, repeat till desired result.
If you over did it, order more stems from PV. I guess I already have like 6 or more modified by my own, bought from them.
I still don't understand what norms or standards or tolerances are you stating with these:
"but i'm pretty sure there are exact tolerances, etc. that need to be adhered to."
Do they have a wind tunnel or any special machine that I'm unknown of to check for airflow???
Are they hiring NASA geeks for designing stems???
DO they have masters in highness and stonerdness???
Am I being sarcastic??? Yes, sorry, I couldn't help it. My apologies at @ vaped4life.
And finally but not last, since when PV has "The Gig" to customize Solo stems??? I didn't know that yet, maybe in Canada, but not here I guess...
BTW,
Who wants carb holes in a Solo GonG stem???
Maybe from 10 people 1 or 2 will like them.
IMO, getting a Y adapter with GonG joints and a glass stopper acting as a carb will make you a fancy customized setup...
(all sold by PV, I got them there, and really cheap quality as well)
You'll have the choice to mix strains, hit 2 vapes (same kind or different) at the same time and clear your huge vapor hits as a pro when using only one vape !!!!
lol
IMO, I don't want to get married to PV, I want more options, and more local options as well.
If you like PV, good for you, I didn't said I don't like them, but, please, they are trying to sell stuff to us, they are FOR PROFIT, so they are not trying to help me,they are not my friends, they are trying to make money on me, IMO If can try to make my own and upgrade them, good for every FC member, and for you too.
Would you stay with PV word only?????
I just wanted a little extra back up for my decision... it is a pretty big price tag for me to justify... but all signs point to yes. Solo will be the side kick, as I prefer it as my portable when the situation calls for it. T1 takes the next slot... Loving all this vaping technology! 
) and while it delivers a nice hit thru the bubbler, there is NO comparison to the Cloud's hit density.
