Sean Sands

Hi I just bought a JVC KD-X340BTS with 6-channel preamp outputs (4-volt) that i bought form Crutchfield it included a Metra 70-1786 Receiver Wiring Harness. It's for a 2000 Mercedes e320 Wagon, with factory Bose sound system. I have the radio turned all the way up everything sounds clear except I'm not getting as much power, or punch from the factory Bose subwoofer in the back as I would like. I feel the factory head unit was louder and gave off more Bass. I would appreciate any help. Thanks.