Found the thread:
Save yourself the time and bs modding your rig. If you want that big radio sound out of your 29 buy one of these and if you need you can make a couple adapter jumpers to use it on any radio you want. Total to your door is under $200 if you pay for the express shipping. Mine was here in a week...
www.worldwidedx.com
Basically the audio amp mod increases the audio gain. The max audio level is limited by the negative feedback resistor. The size of the resistor determines the gain and can be changed if you want to match the audio level you need. The mic level knob on the radio will allow you to turn it down if necessary on the fly too.