Interior Insulation and Sound Deadener

[Dmaxmoe]

I’ve been looking into doing the layered sound treatment as per sound deadener show down and have a few questions for the people who have added some extra layers. My cab is completely stripped and going for paint soon, so I will be adding it as high up the firewall as possible and pretty much everywhere I can reach.

Regarding the factory firewall insulation, is there much use trying to install this over top of the layer of MLV? And does it fit with units like old air and vintage air? My thoughts were to use the push pins that hold the factory insulation to the firewall to instead secure the MLV.

As for the carpet, is there enough room for jute backed carpet, or just try and use no/thin backing? Any issues with accelerator pedal or anything else for that matter after adding all the extra layers?