those batteries are supposed to have a long shelf life..but w/e.. i'll be going with a small odyssey dry cell battery rated at like 700 CCA and is about 6inchs tall, 7 inches long 3 inches wide.. or something of that nature.
I use Stinger SP1000 myself.
Back on topic; removed the MPI tuner and figured out that the previous owner crossed some wires during the install.