Twin Power Lithium Ion Motorcycle Battery vs Drag Specialties AGM battery

Starting a 100 cubic inch S&S motor on a cold day needs a battery with serious cranking power. The 320 CCA AGM battery was ok when it was new; it would usually start the bike before it ran out of juice. But after a few months it just wasn't doing the job any more, so we decided to try one of the new Twin Power 400CCA Lithium-Ion batteries.