I do not mod. My husband does (but he doesn't vape nor smoke). He grew up in the country, his family was poor. So, my husband, his brother & his dad pretty much HAD to learn to fix things instead of paying people to fix them. (at least that is how he explains it) I have no experience with this............as my dad always just called some guy in to do work in our house when I was a kid.
When I look at my husband modding, I see a guy that just "looks" at something & can figure it out. It looks second nature, or instinct to him when I watch him mod. It's almost like he sees it in his brain & can do it. He has a high school diploma, & is a car mechanic by trade, but he can literally fix ANYTHING. One of the reasons I purchased a BMW was so that it could be a challenge to him. So far..........the BMW, german engineering & mechanics have not been a challenge to him.

He did say that it was a PITA to install the 2nd O2 sensor because it's like underneath, up/above the exhaust. BMWs have 2 O2 sensors & this just happens to be the one that goes bad mostly.
Most of the time I just show him a picture of something I want (modded) & he does it. Sometimes he draws it out on paper, other times he doesn't. Now, i'm college educated & do a highly professional job on a daily basis, but I could NEVER figure out some of the stuff he does. He may not know the exacts of physics, but he knows what makes sense.
It's really weird, but my husband & I compliment each other perfectly. He knows stuff that I don't, & I know stuff he doesn't. I tell ya, we would make for one bad azz survival team in the bush if we would ever have to.