I have a 2001 Yukon with woofer, tweeter in front doors, 2-ways in rear doors, small speakers in rear pillars, and 8" subwoofer left rear. The surround is gone from the rear door speakers and subwoofer. The subwoofer is 2 ohm and rear doors are 8 ohm. Anyone know what the factory amp ohm rating is in stock 2001 Yukon (not Bose system)? Can I safely put 4 ohm in the rear doors (I have a set already). Not realy looking to upgrade.... just want to get back to at least factory level of sound...... Thanks!