maybe? you could just get a batcap. Its a capacitor that stores energy. when the bass will hit it will draw alot of current. with the cap in line it uses the energy in the cap instead of the cars electricity. I hope that helped you some.
i mean im not really woried about my audio performance because i have two 1F caps. I'm just worried that with 1100W of RMS I'm gonna be drawing a huge current that my fuses wont be able to handle and my alternator wont be able to replace
Id say you would be fine on the stocker, but you might want to consider an Optima battery. Good luck on getting one to fit though. I tried on my 02 back in the day and the posts were in the wrong spot for the wires to reach. The store I bought it from only had one Optima battery in stock, so there might be different batteries with different post locations to fit your application.
I am in the same situation as you, EGY5 and have had my system for two years already which includes two amps and a sub and have recently had to replace my battery. I have always noticed that the lights have dimmed when I'm pounding my system and I have a cap installed as well and that doesn't seem to help. I have done some reading on our alternators and found that they are only around 75 amps or so. That's weak. I've also read somewhere that others have inquired about replacing them with a higher amp alternator and have been told by subaru that this may wreck our ecus. Does anyone have any suggestions?