Id recommend a Kenwood/JVC HU on the budget side.. mainly JVC. They are owned by Kenwood now and the same model of Kenwood will be as the JVC and the JVC will be a bit cheaper, but same unit. I like
Sonic Electronix to buy my HUs from or
Crutchfield as they usually give free installation kits on most units, and have excellent customer service and reliability. Id look for a Min. of 2 sets of RCAs/3 would be a bonus of 4-5v, with Low Pass high Pass option, and the other options that you like or need. I wouldnt worry too much on a Time Alignment setting for that car, If the unit has it? Its would be a bonus. Find something thats within your budget, and needs. there are some really nice choices out there for under $300 bucks and Ive even been happy with some plain jane units less than $130 bucks believe it or not. I like simplicity. Touch screens drive me nuts. Finger prints on them constantly and wiping them down.UUgh! but nice. do you have Pods for the tweeters you have? Id use them if you can. Alpine make some nice tweets that sound very clean. are the kicker tweets soft dome or metal/alum/titanium? I( like my older KS25 tweets. Pick your Hu out and lets go from there..Im thiunking you are going to need more power on the amplifier side for keeping up with the 15 for front stage. Im thinking 125-200 rms be perfect.
You can always try an Aero-Port for the sub to see if you enjoy it more than sealed. if you do not , you can simply make a square plug to seal it back up without having to make a new enclosure, and can be removed to add the aero port back in again later if you want?