Never Enough Bass

Yea the only battery I have right now is a duralast silver agm and would a 240 amp mechman alt be good enough and what batterys would be good and it's in a dodge charger is there any other things to fix like voltage regulators

The battery is in the trunk on those cars right? That makes things easier. You already have an AGM, but not a high AH one, but instead of having to replace that, you can just add another one. This one just came up on a different thread

https://www.sonicelectronix.com/item-34282-SHURiKEN-SK-BT140.html

140 AH and only $350. Other brands to consider are XS, Full Throttle, Stinger. 

I don't know how much more wattage you want to upgrade to, but you can't have too much electrical support. So, the biggest alternator you can afford from a reputable company....I can't stress that enough.... from a reputable company (mechman, JS, Brand X just off the top of my head) would be best. And, if you ever want to upgrade to more wattage, you wouldn't have to worry about buying another alternator. 

As far as the car goes, that I don't know. If could have system voltage regulators or whatever, a lot of newer cars do, that's something you'd have to look into from someone or somewhere who knows those specific cars. 

Alright I appreciate the info the car is my daily driver and yes the battery is in the trunk makes things a little easier.  But I'm just trying to get the most out of the subs I have and I'll definitely work on the second battery and the alternator. I just finally got the wire to finish my big 3 cause like I said the battery is in the trunk so I have to run my charging wire that far, so you think the subs can handle 3000 watts is a 240 amp alt gonna work sorry for all the questions this is my first time going this big with a system