Odyssey dry cell PC680MJT is what I have in my 348. It only weighs 15.4 pounds. I love it. A bit price though. http://www.odysseybatteries.com I wouldn't try to run a high powered stereo system with it, but as far as starting the car, no problem at all.
I second what earnie says. 25lbs. lighter than stock battery. Lighter weight is like free horsepower and a suspension tuneup!
Top rated by consumers reports is the Walmart "Everstart" in the group 34/78 "universal" size, which should be a direct interchange with the group 34R that fits in most Ferraris (including the 355). Better yet, it is also a "best buy" at only $60! It was "very good" in the life test, and rated "excellent" in reserve capacity and cold cranking amperage performance. It is factory rated at 875 CCA's btw. Also has a 36 month free replacement warranty. If/when I need a new battery for my 355, this is likely what I will get. I hope it fits okay at the bottom, where the battery tray clamp holds down the lip of the battery. I hear the current production Interstate group 34R is now dimensionally too thick, and cannot be properly retained in a 355 battery tray.
