When you detach the battery posts, the computer modules lose some settings. To prevent this, I bought a small battery charger, like a ATV, to hook it to the fuse box and a ground so the modules would stay charged. It worked and all my settings were intact. I went to my local Advanced Auto to get a replacement battery as well. Fits and works fine too.
If you don't do this, your car will have to redetermine the optimal settings for drivings by having the car driven for 50-100 miles. In addition, any DIC settings will be set to default. I couldn't afford for my DIC settings to go back to default because I have an aftermarket stereo.