There are a couple of things that can really annoy me with a car. One is coming back to find broken glass where there should be a window, and the other is using a key to gain access. Enter a Viper alarm.
There was a Mitsubishi Evo 9 in the shop where I was working at the time. It had this annoying alarm that would constantly cause problems. Faulted all the time wouldn’t let the car start, a complete pain in the ass. The owner asked me to remove it completely, and I did. Then I ordered a new harness and a remote that didn’t suck down batteries every 2 days, and re-installed it in my own truck. 9 years later I am happy to report its only had an issue 2 or 3 times since then. The difference of course is the install. If you are careful, route the wiring correctly and make proper connections, 99% of the common alarm problems go away. I have found that generally aftermarket electronics are not near as robust as factory components. They are far more sensitive to voltage fluctuations and changes than a factory part will be so you have to that much more diligent on the installation.
The other couple of things I knocked out is throwing my old Alpine head unit in with an AUX in mod hidden below the ash tray, and installing some now “vintage” Alpha HID’s. These are from back when aftermarket HID kits were Made in Japan and cost $400. I know, but they still work great years later.