just something easier to find, a more general button like Original and Modified
I believe the majority of the cars on the forum are modified. Very common modifications include M30b35 Engines, fixed magnet starters, internally regulated alternators, aftermarket steering wheels, five speed swaps, aluminum radiators, and wheels and tires.
We tend to blend projects and modificaitons together, often comparing the original part to others. So, for example, I was looking at a thread the other day on door brakes. Because of the expense and scarity of original door brakes, some members here have compared a handful of alternatives, from later BMWs and including a Mercedes part. Many of us have gone to the MB part because it is cheap, abundant and works better than the stock door brake. In this way, we not only discuss how to repair something, but also incorporate information on possible modifications. Members can then decide whether to stay original or make a modificaiton when addressing a particular issue.