Currently in my 1989 Jeep Cherokee, I have as follows:
Fi SSD 18 / 9cuft @ 32hz
Old Soundstream amp (temporary) for the SSD
Hifonics HFi100.2 for the alpines
I have a set of 8 gauge wire running to the soundstream amp as its only 15 amps. The Hifonics has 4 gauge wire. I run KnuKonceptz wire.
I plan to do much more, but only when money is available.