Since I seem to be the one non-believier on this issue, I will just add a few comments that will most probably have others saying bad things about both me and my family. When i switched the GT to the discount store battery, I continued to monitor the voltage in the car as it sat for a number of days and compared it to my monitoring of the factory Optima battery that was less than one year old. The discount store battery consistently held voltage MUCH longer than the Optima did. I would put a charger/maintainer on the system , bring it up to max valtage, disconnect the charger and then take a reading every 24 hours, and the discount store battery holds voltage in the GT for litterly weeks, while the Optima fell off rapidly.
This relates to the gauge issue in my opinion, as I understand the gauges need 10.5 volts to function. Any voltage dip below this level sets some activity that drops the gauges out of the system, or so the shop manual says, as I recall.
As to split cases. again, all I can offer is my experience with high performance cars over the years. I have personally seen three Optimas fail due to split cases (yes, it makes a mess). I cannot remember the last time I have seen a regular battery split a case, except at the junk yard where eventually they would freeze and split. I also have blown up a battery (don't lay a timing light on top of a battey and start the engine!)
No fingers are pointed at anybody or any product, just telling the interested members of my experiences.