Previously some posters made me have second thoughts on Trojan batteries. I've seen a number of posts here on the Optima, and don't remember any bad ones. The specs on the Optima Blue D31M look better than the Interstate Megatron MPT-27 and SRM-27 (which fit under my rear seat). The RC or reserve capacity are about the same as the SRM-27 (155 vs 160) and the cranking amps is higher than the MPT-27 (1125 vs 940) as is cold cranking amps (900 vs 750). These specs for the Blue appear the same as for the Commercial  Yellow Top. The Blue has two sets of posts on the top.

So are Optima hype or the ulitimate? 

Not sure if they charge as well with a solar panel...