I recently installed a custom stereo in my 2016 Impala LTZ w/ base OEM system (not Bose). I changed out all the speakers with component tweeters/woofers in all 4 doors + 3 10" subs in trunk. GM has totally messed with the sound by placing filters in OEM amp to turn DOWN low frequency as volume increases + bandpass filters on all channels to make their cheap spkrs sound better using the puny power of OEM amp. Thus changing out spkrs alone will not improve sound. You must overcome the OEM tuning by using another processor to correct deficiencies. Key piece for me was JL Audio Fix 86. Google this piece to see what it does and why you need one (or similar channel summing device). I used OEM amp to provide line level signal to new amps. Hired shop solely to identify (label) factory spkr output wires from amp (in trunk, right side) at 2 connectors. There are 8 channels. Ft Tweet, Ft Woofer, Rear woofer, subs (L+R for each). The OEM amp has sub outputs at connector that go nowhere (no subs in factory set up) so I added these wires. Also added wires for tweets in rear doors. Used OEM spkr wires for everything else. I cut the OEM spkr output wires a few inches passed OEM amp connectors and installed Fix unit. Signal path became this. OEM amp spkr output to Fix 86 input (8 channels). Fix has 6 channel RCA output (Ft, Rr, Subs, L+R) to new JL Audio amps (2) line level input. New amp spkr output back to factory OEM spkr wires previously cut + new wires for rr tweet/subs. Fix unit will equalize all frequencies + sum all channels to get back to full frequency output to new amps. Many amps can handle the slighter higher input signal strength delivered by OEM amp through Fix 86. OEM amp will actually play very clean up to 75% output, so this was max setting used to "tune" system. Sucker now hits crystal clear at 118db! Better yet... each and every function of infotainment system works as before + steering wheel controls operate perfectly since I never changed a thing. You also have balance and fader like before. Total waste of time and money to think about changing out head unit. Why do that? When I sell, I reattach the OEM speaker wires previously cut and put old spkrs back in doors. DIY guy can do this and get shop perhaps to install Fix 86 (or similar device) or at least label wires. Good luck guys!