I have a z140bh in a Chevy Impala. The radio volume only goes up to 40. Is there a way to make it louder ? 

Have you ever seen "This Is Spinal Tap"???

I have a z140bh in a Chevy Impala. The radio volume only goes up to 40. Is there a way to make it louder ? 

Install an amplifier. You can then make it as loud as your speakers can handle. The unit only puts out about 20 watts RMS.

You can try pushing the SLA sliders in audio setup to the max. I found that creates distortion. They'll be no SLA slider for your AM/FM radio.

I know my car came with an amp. Why would I need to install one?

I know my car came with an amp. Why would I need to install one?

Apparently yours isn't powerful enough.

My Grand Prix came with a Monsoon amp. As near as I can tell it put out about 50 watts RMS per channel. I now have a Pioneer 150 watt per channel RMS amp. Setting 20 is as loud as 40 used to be... without the distortion.

Could you tell me the model number of the one you have?

Could you tell me the model number of the one you have?

GM-D8604.

My bad on the output. It's only 100 watts RMS per channel at the 4 ohms my speakers are, which I also replaced with Pioneer units. I'm also running a Bazooka bass tube. It's still miles better than the OEM Monsoon amplifier.

How do i install a pioneer amp? Dont i have to disable the stock one?

Are you just saying the AM/FM isn't "loud", or every source?

Everything. The stock radio is louder, and I am not sure why.

What year is your impala?

sounds like the stock amplifier was used to line level it, and it got changed to pre-out level during the install.