Ok, some examples (my opinion only, all examples are for Improved Production cars):
- Missing headlight allowing cold air to the engine intake? Not vexatious, in my opinion. I'm still faster on the straights than the guy doing this, so I haven't felt the need to bother protesting.
- Lexan side windows, but car is still above minimum weight? Illegal, but I wouldn't bother protesting it. Below minimum weight? Protest. This brings up another issue. Do we even have scales available for CACC events, if a minimum weight protest happens? I can't remember ever taking my car across the scales at a CACC event.
- Cams, porting, high compression pistons, etc. If I knew for sure that somebody was running them, I'd protest. It's very hard to tell in practice without seeing the motor apart, so stuff like this is really up to the conscience of the guy that puts the motor together.
Maybe after the last race of the season we can all do show and tell with the insides of our motors!

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Anyway, a couple conclusions:
- If you see somebody doing something you think is illegal and it bothers you, talk it over with them! Sometimes people don't know what they're doing is illegal, or they think nobody cares. Talk to them and try to settle things without having to throw paper.
- If you can't settle the matter, put in the protest! Don't expect somebody else to do it for you, and don't expect tech to investigate without you asking them to. They aren't police, they're judges.