You have different types of problems and what is a problem for someone else might not be a problem for you or vise versa

1- Cops
2- renewing registration
3- Warranty Loss

In terms of Colors ( renewing registration )
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which is NOT car modification by any means to any car enthusiast, Anything is allowed except of Flat colors ( especially flat black and flat red ), Anything else is OK as long as you do not change more than half of the car and take it to renew registration..

Mechanical upgrades ( Renewing registration, Cops, Warranty Loss)
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You can do ANYTHING, but making yourself sound super loud is asking for trouble especially from locals who are cops.. Meaning, anyone that wears white that works for the police in some way. They can get your car impounded straight from the Villagio parking

Meaning instead of pulling out your resonator and Cats, just put a race Cat to be safe, which you will have to replace when doing your mechanical inspection test as well.

They have something against headers too. Especially when you want to pass the mechanical inspection.

This is problematic to renewing your registration, Cops, Warranty

Cold air intakes, you only lose your warranty, which is very odd.
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Software Tune ups,As long as done on your original ECU, no one
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knows whats going on, even your Dealer at times of maintenance.

Any of the above statements is applicable for the average person, and things might change depending on your last name.