how does this look. the sub will be in the trunk firing into the cabin with the port as well

I'm also debating between the sundown 2500d and the audeque 3500 to run a 15" Fi btl at 1 ohm

my electrical consists of at the moment optima red top up front optima yellow top in the rear, big 3, 0 gauge through out

idk about the box but your gonna need to beef up your electrical if your going with the aq 3500. 2 optimas and a big 3 will probably still result in dimming and voltage drops. Contact iraggi or dc power. I also heard mechman makes a nice alternator as well

how many amp alt do you think would be needed using the 3500, and a sax100.4. (my car is manual everything btw windows locks ect.)

The biggest one you can find for your car, some companies dont list all there alternator options online so you may have to call and/or email them to make sure they have one for your car.

Ideally, your looking at around 200-250 amps for a 2500 watt continuous amp, and 300-350 amp draw for a 3500 watt amp, so plan accordingly. If your stock alternator is 100 amps, then add that in as well. It usually has enough juice just to cover the vehicles electrical draw from the factory. If you are running a second amp, or any other aftermarket electrical, be sure to calculate that in too, remember, ohms law is your friend here.

Adding in more batteries will help if you can't get enough charging, but it is like putting a band aid on a broken bone.