yep i would just upgrade battery, my spl setup was running 2x3000wrms amps and i never had any problems with my yellowtop and a larger single ground (72mm2) off the battery
i can try and collect friday or someone can drop it off to me at work. Ill be at foxglove tomorrow from 10-4
or maybe if san go's tonight i can collect from him maybe as not far. Im pretty flexible when it comes to this as so serious