we;; hids use less power than the nomral bulbs so thats not an issue,now the sound system, well if the car is running all the power is coming form the alternator.. so i think you wont be having an issue on that also, but if you head light dims on heavy base than big battery wont even solve that, you will be needing a capacitor or something like that..
i think that alto comes with 36AH battery, well i step upto 45 i guess, and you will be fine.. and i have my good experiences with all these local made batteries( by this i dont mean the batteries reconditioned at a hoem scale factory), brands like ags, volta etc etc.
cheers