don't expect any 6.5" class car speaker to play below 100hz. realistically, you don't need anything lower. Go with a sub that can comfortably be crossed over at 150hz. You mentioned an 8" sub, the JL 8w7 and either of those Focals would make a fantastic system with a 5ch amp like the JL VX1000/5i (which has a full featured DSP built in).