Whats the side effect of getting a chip for your vehicle?

I just bought a chip and i wanna make sure it doesnt mess up my engine. does anyone know what the side effects of getting a chip are?

what brand chip did you buyand what car do you have?

I think its redline and i got an 04 lancer oz rally. this chip says its especially made for mits though not that i have installed yet or anything but i was just wondering

if it requires removing your ECU and installing it into it then the only downside is that it requires you to run premium fuel and sometimes it idles a little rough. If its the kind that you have to splice a wire from your Intake Air Temperature Sensor, then all it does is make you get lousy gas mileage and you should try to get your money back.