I tried one of these a while a few years back and found it wouldn't crank the engine so I invested in 600CCA SBB lithium battery. They have an OC voltage around 13.4V and crank the engine over much faster than an SLA. The good thing is they are a lot smaller and only weigh about 1 -2 KGs. Weight, space savings and more cranking grunt. My MSD ignition is happier too.
I've had similar ultralight batteries in my Exige, but with the mysterious current draw if I didn't isolate the battery it would be dead after a few days. I wouldn't bother in a zed.