I've also came up with a NPC mod for this rig as well. I will post a pic if I can figure out how.
This was just a preliminary test photo to show location of the mod. The final mod on my radio used, I think, a 560 ohm resistor in series with the diode to limit the amount of negative peak compression. A one K ohm variable could be incorporated and be adjusted for proper wave form for a given carrier for optimal performance over a wide range. If only a diode is used the negative peaks will not make it to zero and badly distorts and flattens the negative wave form.
This isn't a huge swinging mod but it does wake up the radio and give a cleaner sound if the radio is adjusted properly in the service menus.
Hope this helps, these are great sounding rigs when set up properly!
Panic Attack Got Down!