Im usually never gas capped? Maybe you dont have enough pylons? Pylons cost 20/40 and produce 1 minerals 2 gas.
To upgrade it, you need 60 minerals 100 gas. Which means you would have more gas. But then the updated version produces 4 minerals 3 gas. Thats an improvement of 3 minerals and 1 gas. Instead of spending 60/100 to upgrade, you could make more regular pylons. roughly 2 pylons plus some left over. This becomes 2 mineral 4 gas improvement instead of a 3 mineral 1 gas improvement. If you want to play gas heavy, then instead of upgrading your pylons, just build more pylons.
Tl&dr build more regular pylons.