I have owned a blue top for several years. I'm going to trunk mount it in my cobra, so I have not tried it in a mustang yet, but it worked well in two other cars, and it also had enough juice to jump start a car after sitting for 9 months without any charging.
They are damn good batteries and well worth the price. The blue top is not a deep cycle, it just has more CCA's and it was the same price as a red top. I just wish I new where to get one for $60 like svt5150.