I have an LOC tied to the OEM sub that powers my extra subs. Everything else factory, but I put 55W RF speakers in instead of the OEM 35W. Still powered by the factory HU since I have NAV and wanted to keep the truck diagnostics. I think one guy put in an aftermarket HU and kept his NAV, but he had to put the OEM head in the glove box to keep powering the NAV unit. If you get rid of it completely on our trucks that have it you lose those diagnostic features.