I have a stock auto Lexus IS300 with nearly 160,000 miles with absolutely no problems other then the navigation system, which is a common problem. It's driven in Southern California so the heat, road conditions, and traffic should be put into consideration. With all regular maintenance (not including any major repair), what is the first vital (necessary to drive daily) component to have issues on this car??? I've heard the transmission so I'm planning on installing a small transmission cooler. I'm wondering what other precautions I should take (valve body upgrade, new valves, radiator upgrade, fuel line upgrade, fuel pump upgrade, lighter pulleys, etc.). Thanks.