I want to know how i can make certain upgrades like terran infantry weapons for example be able to be fully upgraded to 255. I have it so 255 upgrades is their max but i need to have other buildings built to do this. Also how can i make some things, like terran infantry armor for example not show up at all so they cannot be changed?

I use SCMDraft 2

Make maxiumum 0 I'm guessing, I've never worked with this stuff. And you always need more buildings to upgrade more. Which is why you place like your Science Facility in the middle of nowhere.

how do they do ti in tarpit d though?

I don't completely understand the question, but I'll do the best to help you.

To get past upgrade level one, you need the tech building. In the case of Terran, this is the Science Facility. There is no way to exceed this limit without giving the player the tech building. However, once they are done upgrading the building can be given back. You see this all the time in defences.

You can theoretically set any upgrade from 0-255 (since it's a byte). If you set the maximum as the same as the start level, it will not appear as upgradeable for the player. Otherwise, they can keep upgrading until they hit the maximum level.

If I didn't answer you question, clarify your request

To make the armor upgrade disappear, just set the maximum level for the upgrade to 0.
And for up to 255, just place a science facility for each player... I don't see the problem in that.

If you start the default upgrades at 3, they'll never need tech buildings no matter how high you go. You'll just have to adjust unit stats accordingly. (or not at all, if it applies to all units evenly enough...)

if u use Scm2 set it to 0