Worthless reject member
i think the term applies to anything that isn't forced induction, nitrous, or anything that doesn't require work to the inside of the motor, top end included.Would you consider a OTRCAI a bolt on? For many of those you have to cut things, redo wiring and other bits and pieces. Just sayin'. I'd consider a Maggie the ultimate bolt on. Heck, I went deeper into the engine to install my 1.8 rockers that you have to to install a blower. Not saying it was more work, just that I was actually into the mechanics of the engine itself doing rockers which you certainly don't have to do to install a blower. Depends on how you want to define the term I guess.
And that is really something that, iirc, is a very group-focused definition. "bolt-on" to one group of enthusiasts may not have the same meaning to another. i've heard the term applied to cams, heads, superchargers, etc, because they are basically involved parts swaps.
i think the first definition really makes it a "level" to modification. so if you lose you can say "well i just had bolt-ons, lulz, you had all dat modawerk" or if you win against something that has had more modifications done you can be like "lulz i onleh haz bolt-ons."