Hi Bat,
Yes, Electrathon America has approved new battery rules to allow the Optima yellow top batteries. The yellow tops are deep-cycle and (supposedly) good for about 300 charge/discharge cycles as opposed to the red tops which are good for 50 - 60 cycles. The reasoning was that they cost about 30% more, but last 500% longer. In order to make them legal, the maximum overall weight had to be raised so that other manufacturers equivalent batteries could also be used. As soon as my personal budget allows I'm going to get a couple of them to replace a couple of my older red tops, but I will still be using my remaining red tops until I wear them out...

Glad you got your "tow car" up & runnig again; there are a bunch of races coming up...