If you want to treat a copper like an idiot eg: "Its a stock N/A sir, I swear", then you will be treated like a smartarse and probably have the book thrown at you.
Also, as mentioned, what happens if you kill someone, maim or just destory someone else's car and don't have any insurance ? Just a case of "I hope no one saw me hit that person/car?".
Your not allowed too have a turbocharged car - accept it.