I've been in HK for almost 3 years, been driving for 1+ years now and modded my car as much as I can afford... (which isn't much...!)
In the 1+ years I've been driving, I learned a thing or two, mostly from the members here:
- Any part that is not original (didn't come pre-installed with the car) are deemed illegal mods. Yes - you're absolutely right, even a sweet set of 19" BBS are "technically" illegal if the cops wanted to nail you.
- BMW perf. vs. Aftermarket = purely personal preference.
However, for body kits, I would go with original parts. More expensive but saves on the headache of fitment issues.
Anything with a "BMW Performance" logo is usually more expensive. e.g: Brembo brakes vs BMW Performance. Recaro Seats vs. BMW Performance seats (same thing, just different stitching = more $$$).
At the end, it all depends on your personal taste. After all, your car is an extension of your artistic and creative side
- Performance wise: I do not think BMW makes anything that will significantly increase your car's output.
Have fun modding mate...