I have a pioneer Avic-z110bt installed in my car . I noticed that the spears in the rear doors sound low. so i wired them separately to the HU. Made a lil improvement .. but i feel like when i have the factory stereo installed i get better crisp quality audio.. ??? Assuming that you get the best when using a monsoon compatible factory hU. Do you guys recommend wiring all the speakers directly to the HU and not use the factory Harness. Or should i buy a 4 channel amp power it directly to that. Trying to get some ideas. I have 1000watt amp powering subs in the trunk. I also have the factory sub still connected. Gmos-04