Sir
I have a 2005 Civic Exi PROSMATEC, it has a 90AMP alternator plus AGS NS60 (45AH premium Acid battery), when I installed 308D4, and it starts producing some heavy bass my head unit and dashboard lights start to dim, and it was without a mono class D AMP.
your alternator and Acid batteries cant be more then 80% efficient of their rating, and what will happen in summer when you'll be using A/C
Besides, you'll be paying only 2,000-2,500Rs at most after giving your almost new battery, then what's the catch.
Prevention is better then cure.