my 2005 z71 is in need of some speaker replacement. This has the the Bose system with the navigation system head unit. I'm just wanting to replace the speakers with something that would be an OEM type replacement. Not wanting to blow my ear drums but wanting good quality of sound. Does anyone have some suggestions?
I'm not sure if you are looking for something with improved sound, or if your current Bose speakers are damaged and need to be replaced.
In my opinion, if you like the sound of a Bose system, then replacing the speakers with something else is not going to give you a dramatic improvement in sound quality.
In my '07 Denali, I replaced the entire Bose system, as I prefer a different sound profile than what the Bose system delivers. The Bose speakers that I replaced were 6 1/2" with 1.9 ohm impedance (stamped on the speaker magnet) in the front doors, and 5 1/4" with 3.6 ohm impedance (stamped on the speaker magnet) in the rear doors.
Normally, I would recommend that you try to match the replacement speaker impedance as closely as possible to the original speaker impedance, as it presumably is matched to the existing power amplifier driving it. However, I don't believe that you will find a lot of 6 1/2" 2 ohm speakers on the market, and the few that exist will be expensive. If you replace the 6 1/2" 2 ohm speaker with a 4 ohm speaker, chances are that you may get less sound volume out of the replacement speakers than you get out of your current Bose speakers, but it should not hurt the amplifier.
I used Alpine SPS-610C Component for the front doors, and Alpine SPS-610 Coax for the rear doors, since I already had them installed for 5 years in my '97 Yukon, and just re-used them on the '07 Denali. I believe that an Alpine speaker would give you good sound at a reasonable price point.
Before making a final speaker selection, though, I strongly recommend as a starting point that you look at your existing speakers and determine what their ohm impedance is, as your Bose system may have different speakers and impedances than mine.
Hopefully, this is useful to you.