What size amp

[wizart383]

I would stick with those subs since you already have them. If your planing on running around 2000 watts you might want to also add a second battery in the rear

[photochrisb931]

I agree with Wizart run those subs for the moment and add a second agm bat in the rear. Congrats on the alt nice foresight. Place your money at this point in the electrical and a solid amp then upgrade those subs in the future but if you have the money for better subs by all means upgrade them.