I think he doesn't want a specific mod, but he means having like a secondary game options tab in which you get the stats, or at least the costs, of all units in the game, and you can customise them as you please, before hitting start.
Practically, a way to have units options and costs editable, like the properties already may be.
Not sure what should happen in cases like the NWO artillery.
@redrum I dunno if you played the A&A computer game (3rd edition)? That had something like that, at start game, in which you could have raised the defence value of Tank from 2 to 3 etc..
Making all of a series of mods for changing maybe only 1 stats each is kind of overkill, so in that I can see this having its raison d'être.
Anyways, @Irontooth changing basic stats is easy. Search for the "downloadedMaps" folder. Then, you can unzip the map that you want. You probably need to rename the folder removing the "-master" end, when unzipped. Then, you just need to click your way into till entering the "games" folder. There you can open the games' xml and you will see basic stuff is easy to reference and change, but better you copy paste the entire xml and rename the info name (it is at the start of the xml), then do your tweaks on the copy, while letting the original be (this way you will be able to select either the original or your mod).
For Revised and v4, those units are all pretty close, I don't think either of your choices would balance out well.
If you lower the armour cost by 1, and nothing else, the artillery becomes worthless and the armour becomes incredibly spammy.
If you lower the infantry cost by 1, and nothing else, the artillery becomes almost worthless, and the armour becomes a hard buy (you basically have NWO with overpriced artillery).
If you lower both the infantry and the armour by 1, the artillery becomes absolutely worthless and air units become almost worthless for land powers (hard to fund the luftwaffe with inf at 2 and armour at 4).