Ever asked for the code under which they are justified in searching your car? Don't object, just make sure you are told under what legal authority they are taking this action. If the police are non-responsive, well, that's just fodder for future complaints.
Better yet, carry quotes of the legislation dealing with your questionable modifications. The issue of headlight colour and output, window tint, etc. are all laid out. Have that printed out, with act, section, paragraph cited, so you can respond when an cop is being an ass. As a suggestion, don't pull it out unless he's threatening you with a ticket and refuses to give you a clear explanation of where you are violating the law.
Most states only regulate private conversations and recording devices. You are having a conversation on the street -- by definition a public place. Just as anything you do in a public place is subject to public scrutiny, so too is anything you say. It'd require some impressive legal wrangling to say citizens don't have the right to record their encounters in public with police -- that would mean media wouldn't be allowed to secretly videotape anybody doing anything in public. >

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And maybe keep a log of when you were pulled over the explanation you were given for being detained. If you can lay out a pattern of barely justified stops, you build a strong case. The media particularly like timelines, if it gets bad enough you need publicity.