my old optima red top recently died. It was actually too small- short, I added a piece of rubber for the factory hold down to be secure. What group size fits the best under the factory hold down without modification? Also, are the new optima not as good as the ones from 10 years ago? I'd like another AGM because the lead acids tend to vent. I don't want my battery to vent and potentially corrode anything under the hood. Thanks.