1. the factory head unit wll work fine at 4 ohms, if you use lower ohm speakers you will get more volume but it will be harder on the stereo but you should be just fine.
2. there is no benefit to either 8 or 4 ohms, its just the resistance, some high end home speakers can be anywhere from 2-16 ohms. it all depends on how the system was designed.
Generally, lower ohms ---> more current ---> more power this is true until you turn up the volume until it distorts (true for any speaker system) just keep the volume to a level that still sounds good, any crunching or farting sounds and your gonna cause problems.
"-@--------@--" 1990 SSE " Black Ice " 220,000+ kms, GX3, sunroof
16" Streetwear Diablo wheels | Blazer Fog Lamps | Silverstar 9005 low beams | Mesh Grille | STB | '94 Top end | Delco Type 2 Ignition | Blue interior LEDs | LED 3rd brake light | Auto-dimming rear view mirror | Pioneer DEH-P7600MP | Rockford 5 1/4 Components and 6x9s
Daily driver : '95 Buick Regal Custom | Blue under dash LEDs | Infinity 5 1/4 components | 8 Inch sub under dash | 12 inch Bazooka sub in trunk | Rockford 4 ch amp | Trunk mounted EQ | Pulsing trunk LEDs