I've seen alot of threads about what Optima battery fits best in the 03/04 Cobra so I decided to make a How To. So first off you need to pick up an Optima Battery (Part # 34-78, Model # 3478DT.) The only tools you should need is a 5/16" socket and rachet with a extension and a small saw. Remove the current battery then remove the battery tray by removing the 3 5/16" bolts one in the center and 2 on the side. Set the Optima battery in side the tray, you will notice its a little to wide mark the side of the tray that sits closest to the headlight useing the battery as a guide. Cut the side off the tray. Fit test the battery and cut more if needed. Install the two adapters that come with the battery. Install the battery tray, slide in your new Optima and tighten it down, connect the terminals and enjoy!