A modification I made is a campaign that is basically the regular campaign except you get a little more money. I don't like fighting the weaker aliens in the easier campaigns because I'm pretty good at the tactical part of the game and fighting the weaker aliens is boring, but I'm not very good at the budget/management part so I made that easier while keeping the aliens from getting weaker. I don't think that is a unreasonable change I just wanted a difficultly that matched my uneven skills so the game doesn't get boring or too difficult. I think the game is well balanced and makes for a good challenge. I just mixed and matched that balanced to create a difficultly that is challenges my skills appropriately.
The reason I wanted to know what the installation limit is, I was curious and the fact that I couldn't find it made me more curious. I honestly didn't have any plans on changing it.