For your 348, you're going to want a $12 aftermarket zinc anode from
WWW.JCWhitney.com (search under "Cooling"). This disposable part sacrifices itself, over time, so that electrolysis attacks it instead of your engine and radiators.
For cooling, you're going to want Red Line's "Water Wetter" or the new "40 Below" product. I've used one or the other constantly over the past ten years. They both work well to drop your water temp back to the dead center of your H2O temp gauge.
Red Line's synthetic shock-proof gear oil actually lets you shift your 348 into 2nd gear when cold.
WWW.Durable1.com offers a great shift bushing upgrade to improve the smoothness of all of your shifts, and they also sell a Krank Kase vent that will cut out minor oil seeps and give you an extra 4 horsepower.
WWW.hyper-flow.com/348.htm sells high performance Ferrari catalytic converters.