as far as sub goes, I just installed one 12" 4ohm with 300watt peak and supplied power to it with a "D" class mono amp that has 200watt RMS so it would be clean and have room to play. It absolutely rocks my hatchback when i turn it up. Very clean crip and I only have the gain on a 30% turn with 70% left on the amp. Never cuts off and BOOMS when I need it!!! Got a ported slimline light box from best buy to house the 12" and I just laid it down facing upward behind in the middle of the fold down seats.
'90 lx hatch - Midnight Metallic
-Milled/Ported - Gt40p_Cobra Intake - "Ecam" -280rwhp_319rwtrq- w/ AC climate control
Custom Tune Chip with all bolt on's, including electric fan. pulleys - 5spd - 3:55 gears
High Velocity Stage Down - 83mm Pro-M, 73mm bbk tube, 65mm TB
...daily driven and pinching ponies ain't cheap.
Little oil pump shafting and lifter tappin' ass in