Relatively new to air guns, can you modify CO2 air guns?

Before you say “Google is free,” we all know Google’s algorithm literally hides any juicy information on anything semi-controversial… I tried & gave up after every answer I saw just tells you to clean the gun & use lighter bullets🤦‍♂️

I just got a Umarex MP40 that is cool as hell, it shoots .177 steel BBs. Are there any cool modifications that you’re not supposed to do/wouldn’t recommend?

I have 2 shotguns & 3 rifles, but I can’t just shoot them in the backyard whenever I want lol